sched: Move numa_balancing sysctls to its own file

The sysctl_numa_balancing_promote_rate_limit and sysctl_numa_balancing
are part of sched, move them to its own file.

Signed-off-by: Kefeng Wang <w

sched: Move numa_balancing sysctls to its own file

The sysctl_numa_balancing_promote_rate_limit and sysctl_numa_balancing
are part of sched, move them to its own file.

Signed-off-by: Kefeng Wang <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

memory tiering: rate limit NUMA migration throughput

In NUMA balancing memory tiering mode, if there are hot pages in slow
memory node and cold pages in fast memory node, we need to promote/demote
h

memory tiering: rate limit NUMA migration throughput

In NUMA balancing memory tiering mode, if there are hot pages in slow
memory node and cold pages in fast memory node, we need to promote/demote
hot/cold pages between the fast and cold memory nodes.

A choice is to promote/demote as fast as possible. But the CPU cycles and
memory bandwidth consumed by the high promoting/demoting throughput will
hurt the latency of some workload because of accessing inflating and slow
memory bandwidth contention.

A way to resolve this issue is to restrict the max promoting/demoting
throughput. It will take longer to finish the promoting/demoting. But
the workload latency will be better. This is implemented in this patch as
the page promotion rate limit mechanism.

The number of the candidate pages to be promoted to the fast memory node
via NUMA balancing is counted, if the count exceeds the limit specified by
the users, the NUMA balancing promotion will be stopped until the next
second.

A new sysctl knob kernel.numa_balancing_promote_rate_limit_MBps is added
for the users to specify the limit.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: "Huang, Ying" <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: osalvador <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Wei Xu <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Zhong Jiang <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

sched: Move energy_aware sysctls to topology.c

move energy_aware sysctls to topology.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniont

sched: Move energy_aware sysctls to topology.c

move energy_aware sysctls to topology.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move cfs_bandwidth_slice sysctls to fair.c

move cfs_bandwidth_slice sysctls to fair.c and use the
new register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@

sched: Move cfs_bandwidth_slice sysctls to fair.c

move cfs_bandwidth_slice sysctls to fair.c and use the
new register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move uclamp_util sysctls to core.c

move uclamp_util sysctls to core.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
S

sched: Move uclamp_util sysctls to core.c

move uclamp_util sysctls to core.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move rr_timeslice sysctls to rt.c

move rr_timeslice sysctls to rt.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Sig

sched: Move rr_timeslice sysctls to rt.c

move rr_timeslice sysctls to rt.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move deadline_period sysctls to deadline.c

move deadline_period sysctls to deadline.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@

sched: Move deadline_period sysctls to deadline.c

move deadline_period sysctls to deadline.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move rt_period/runtime sysctls to rt.c

move rt_period/runtime sysctls to rt.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniontec

sched: Move rt_period/runtime sysctls to rt.c

move rt_period/runtime sysctls to rt.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move schedstats sysctls to core.c

move schedstats sysctls to core.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Sig

sched: Move schedstats sysctls to core.c

move schedstats sysctls to core.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

sched: Move child_runs_first sysctls to fair.c

move child_runs_first sysctls to fair.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@uniont

sched: Move child_runs_first sysctls to fair.c

move child_runs_first sysctls to fair.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

show more ...

NUMA balancing: optimize page placement for memory tiering system

With the advent of various new memory types, some machines will have
multiple types of memory, e.g. DRAM and PMEM (persistent memor

NUMA balancing: optimize page placement for memory tiering system

With the advent of various new memory types, some machines will have
multiple types of memory, e.g. DRAM and PMEM (persistent memory). The
memory subsystem of these machines can be called memory tiering system,
because the performance of the different types of memory are usually
different.

In such system, because of the memory accessing pattern changing etc,
some pages in the slow memory may become hot globally. So in this
patch, the NUMA balancing mechanism is enhanced to optimize the page
placement among the different memory types according to hot/cold
dynamically.

In a typical memory tiering system, there are CPUs, fast memory and slow
memory in each physical NUMA node. The CPUs and the fast memory will be
put in one logical node (called fast memory node), while the slow memory
will be put in another (faked) logical node (called slow memory node).
That is, the fast memory is regarded as local while the slow memory is
regarded as remote. So it's possible for the recently accessed pages in
the slow memory node to be promoted to the fast memory node via the
existing NUMA balancing mechanism.

The original NUMA balancing mechanism will stop to migrate pages if the
free memory of the target node becomes below the high watermark. This
is a reasonable policy if there's only one memory type. But this makes
the original NUMA balancing mechanism almost do not work to optimize
page placement among different memory types. Details are as follows.

It's the common cases that the working-set size of the workload is
larger than the size of the fast memory nodes. Otherwise, it's
unnecessary to use the slow memory at all. So, there are almost always
no enough free pages in the fast memory nodes, so that the globally hot
pages in the slow memory node cannot be promoted to the fast memory
node. To solve the issue, we have 2 choices as follows,

a. Ignore the free pages watermark checking when promoting hot pages
from the slow memory node to the fast memory node. This will
create some memory pressure in the fast memory node, thus trigger
the memory reclaiming. So that, the cold pages in the fast memory
node will be demoted to the slow memory node.

b. Define a new watermark called wmark_promo which is higher than
wmark_high, and have kswapd reclaiming pages until free pages reach
such watermark. The scenario is as follows: when we want to promote
hot-pages from a slow memory to a fast memory, but fast memory's free
pages would go lower than high watermark with such promotion, we wake
up kswapd with wmark_promo watermark in order to demote cold pages and
free us up some space. So, next time we want to promote hot-pages we
might have a chance of doing so.

The choice "a" may create high memory pressure in the fast memory node.
If the memory pressure of the workload is high, the memory pressure
may become so high that the memory allocation latency of the workload
is influenced, e.g. the direct reclaiming may be triggered.

The choice "b" works much better at this aspect. If the memory
pressure of the workload is high, the hot pages promotion will stop
earlier because its allocation watermark is higher than that of the
normal memory allocation. So in this patch, choice "b" is implemented.
A new zone watermark (WMARK_PROMO) is added. Which is larger than the
high watermark and can be controlled via watermark_scale_factor.

In addition to the original page placement optimization among sockets,
the NUMA balancing mechanism is extended to be used to optimize page
placement according to hot/cold among different memory types. So the
sysctl user space interface (numa_balancing) is extended in a backward
compatible way as follow, so that the users can enable/disable these
functionality individually.

The sysctl is converted from a Boolean value to a bits field. The
definition of the flags is,

- 0: NUMA_BALANCING_DISABLED
- 1: NUMA_BALANCING_NORMAL
- 2: NUMA_BALANCING_MEMORY_TIERING

We have tested the patch with the pmbench memory accessing benchmark
with the 80:20 read/write ratio and the Gauss access address
distribution on a 2 socket Intel server with Optane DC Persistent
Memory Model. The test results shows that the pmbench score can
improve up to 95.9%.

Thanks Andrew Morton to help fix the document format error.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: "Huang, Ying" <[email protected]>
Tested-by: Baolin Wang <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Wei Xu <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: zhongjiang-ali <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Feng Tang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

sched: move autogroup sysctls into its own file

move autogroup sysctls to autogroup.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <nizhen@unionte

sched: move autogroup sysctls into its own file

move autogroup sysctls to autogroup.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...

hung_task: move hung_task sysctl interface to hung_task.c

The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this

hung_task: move hung_task sysctl interface to hung_task.c

The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong. The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

So move hung_task sysctl interface to hung_task.c and use
register_sysctl() to register the sysctl interface.

[[email protected]: commit log refresh and fixed 2-3 0day reported compile issues]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Xiaoming Ni <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Amir Goldstein <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Benjamin LaHaise <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Iurii Zaikin <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Qing Wang <[email protected]>
Cc: Sebastian Reichel <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Stephen Kitt <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Antti Palosaari <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Clemens Ladisch <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Joseph Qi <[email protected]>
Cc: Julia Lawall <[email protected]>
Cc: Lukas Middendorf <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Phillip Potter <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Douglas Gilbert <[email protected]>
Cc: James E.J. Bottomley <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: John Ogness <[email protected]>
Cc: Martin K. Petersen <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

sched/sysctl: Move extern sysctl declarations to sched.h

Since commit '8a99b6833c88(sched: Move SCHED_DEBUG sysctl to debugfs)',
SCHED_DEBUG sysctls are moved to debugfs, so these extern sysctls in

sched/sysctl: Move extern sysctl declarations to sched.h

Since commit '8a99b6833c88(sched: Move SCHED_DEBUG sysctl to debugfs)',
SCHED_DEBUG sysctls are moved to debugfs, so these extern sysctls in
include/linux/sched/sysctl.h are no longer needed for sysctl.c, even
some are no longer needed.

So move those extern sysctls that needed by kernel/sched/debug.c to
kernel/sched/sched.h, and remove others that are no longer needed.

Signed-off-by: Hailong Liu <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...

sched: Warn on long periods of pending need_resched

CPU scheduler marks need_resched flag to signal a schedule() on a
particular CPU. But, schedule() may not happen immediately in cases
where the cu

sched: Warn on long periods of pending need_resched

CPU scheduler marks need_resched flag to signal a schedule() on a
particular CPU. But, schedule() may not happen immediately in cases
where the current task is executing in the kernel mode (no
preemption state) for extended periods of time.

This patch adds a warn_on if need_resched is pending for more than the
time specified in sysctl resched_latency_warn_ms. If it goes off, it is
likely that there is a missing cond_resched() somewhere. Monitoring is
done via the tick and the accuracy is hence limited to jiffy scale. This
also means that we won't trigger the warning if the tick is disabled.

This feature (LATENCY_WARN) is default disabled.

Signed-off-by: Paul Turner <[email protected]>
Signed-off-by: Josh Don <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...

sched: Move SCHED_DEBUG sysctl to debugfs

Stop polluting sysctl with undocumented knobs that really are debug
only, move them all to /debug/sched/ along with the existing
/debug/sched_* files that a

sched: Move SCHED_DEBUG sysctl to debugfs

Stop polluting sysctl with undocumented knobs that really are debug
only, move them all to /debug/sched/ along with the existing
/debug/sched_* files that already exist.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Tested-by: Valentin Schneider <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...

sched/uclamp: Add a new sysctl to control RT default boost value

RT tasks by default run at the highest capacity/performance level. When
uclamp is selected this default behavior is retained by enfor

sched/uclamp: Add a new sysctl to control RT default boost value

RT tasks by default run at the highest capacity/performance level. When
uclamp is selected this default behavior is retained by enforcing the
requested uclamp.min (p->uclamp_req[UCLAMP_MIN]) of the RT tasks to be
uclamp_none(UCLAMP_MAX), which is SCHED_CAPACITY_SCALE; the maximum
value.

This is also referred to as 'the default boost value of RT tasks'.

See commit 1a00d999971c ("sched/uclamp: Set default clamps for RT tasks").

On battery powered devices, it is desired to control this default
(currently hardcoded) behavior at runtime to reduce energy consumed by
RT tasks.

For example, a mobile device manufacturer where big.LITTLE architecture
is dominant, the performance of the little cores varies across SoCs, and
on high end ones the big cores could be too power hungry.

Given the diversity of SoCs, the new knob allows manufactures to tune
the best performance/power for RT tasks for the particular hardware they
run on.

They could opt to further tune the value when the user selects
a different power saving mode or when the device is actively charging.

The runtime aspect of it further helps in creating a single kernel image
that can be run on multiple devices that require different tuning.

Keep in mind that a lot of RT tasks in the system are created by the
kernel. On Android for instance I can see over 50 RT tasks, only
a handful of which created by the Android framework.

To control the default behavior globally by system admins and device
integrator, introduce the new sysctl_sched_uclamp_util_min_rt_default
to change the default boost value of the RT tasks.

I anticipate this to be mostly in the form of modifying the init script
of a particular device.

To avoid polluting the fast path with unnecessary code, the approach
taken is to synchronously do the update by traversing all the existing
tasks in the system. This could race with a concurrent fork(), which is
dealt with by introducing sched_post_fork() function which will ensure
the racy fork will get the right update applied.

Tested on Juno-r2 in combination with the RT capacity awareness [1].
By default an RT task will go to the highest capacity CPU and run at the
maximum frequency, which is particularly energy inefficient on high end
mobile devices because the biggest core[s] are 'huge' and power hungry.

With this patch the RT task can be controlled to run anywhere by
default, and doesn't cause the frequency to be maximum all the time.
Yet any task that really needs to be boosted can easily escape this
default behavior by modifying its requested uclamp.min value
(p->uclamp_req[UCLAMP_MIN]) via sched_setattr() syscall.

[1] 804d402fb6f6: ("sched/rt: Make RT capacity-aware")

Signed-off-by: Qais Yousef <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

show more ...

sched/deadline: Impose global limits on sched_attr::sched_period

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected

Commit 401c636a0eeb ("kernel/hung_task.c: show all hung tasks before
panic") introduced a change in that we star

kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected

Commit 401c636a0eeb ("kernel/hung_task.c: show all hung tasks before
panic") introduced a change in that we started to show all CPUs
backtraces when a hung task is detected _and_ the sysctl/kernel
parameter "hung_task_panic" is set. The idea is good, because usually
when observing deadlocks (that may lead to hung tasks), the culprit is
another task holding a lock and not necessarily the task detected as
hung.

The problem with this approach is that dumping backtraces is a slightly
expensive task, specially printing that on console (and specially in
many CPU machines, as servers commonly found nowadays). So, users that
plan to collect a kdump to investigate the hung tasks and narrow down
the deadlock definitely don't need the CPUs backtrace on dmesg/console,
which will delay the panic and pollute the log (crash tool would easily
grab all CPUs traces with 'bt -a' command).

Also, there's the reciprocal scenario: some users may be interested in
seeing the CPUs backtraces but not have the system panic when a hung
task is detected. The current approach hence is almost as embedding a
policy in the kernel, by forcing the CPUs backtraces' dump (only) on
hung_task_panic.

This patch decouples the panic event on hung task from the CPUs
backtraces dump, by creating (and documenting) a new sysctl called
"hung_task_all_cpu_backtrace", analog to the approach taken on soft/hard
lockups, that have both a panic and an "all_cpu_backtrace" sysctl to
allow individual control. The new mechanism for dumping the CPUs
backtraces on hung task detection respects "hung_task_warnings" by not
dumping the traces in case there's no warnings left.

Signed-off-by: Guilherme G. Piccoli <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

sysctl: pass kernel pointers to ->proc_handler

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from u

sysctl: pass kernel pointers to ->proc_handler

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from userspace in common code. This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig <[email protected]>
Acked-by: Andrey Ignatov <[email protected]>
Signed-off-by: Al Viro <[email protected]>

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sched/uclamp: Add system default clamps

Tasks without a user-defined clamp value are considered not clamped
and by default their utilization can have any value in the
[0..SCHED_CAPACITY_SCALE] range

sched/uclamp: Add system default clamps

Tasks without a user-defined clamp value are considered not clamped
and by default their utilization can have any value in the
[0..SCHED_CAPACITY_SCALE] range.

Tasks with a user-defined clamp value are allowed to request any value
in that range, and the required clamp is unconditionally enforced.
However, a "System Management Software" could be interested in limiting
the range of clamp values allowed for all tasks.

Add a privileged interface to define a system default configuration via:

/proc/sys/kernel/sched_uclamp_util_{min,max}

which works as an unconditional clamp range restriction for all tasks.

With the default configuration, the full SCHED_CAPACITY_SCALE range of
values is allowed for each clamp index. Otherwise, the task-specific
clamp is capped by the corresponding system default value.

Do that by tracking, for each task, the "effective" clamp value and
bucket the task has been refcounted in at enqueue time. This
allows to lazy aggregate "requested" and "system default" values at
enqueue time and simplifies refcounting updates at dequeue time.

The cached bucket ids are used to avoid (relatively) more expensive
integer divisions every time a task is enqueued.

An active flag is used to report when the "effective" value is valid and
thus the task is actually refcounted in the corresponding rq's bucket.

Signed-off-by: Patrick Bellasi <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alessio Balsini <[email protected]>
Cc: Dietmar Eggemann <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Morten Rasmussen <[email protected]>
Cc: Paul Turner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Quentin Perret <[email protected]>
Cc: Rafael J . Wysocki <[email protected]>
Cc: Steve Muckle <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Todd Kjos <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: Viresh Kumar <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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sched/topology: Introduce a sysctl for Energy Aware Scheduling

In its current state, Energy Aware Scheduling (EAS) starts automatically
on asymmetric platforms having an Energy Model (EM). However,

sched/topology: Introduce a sysctl for Energy Aware Scheduling

In its current state, Energy Aware Scheduling (EAS) starts automatically
on asymmetric platforms having an Energy Model (EM). However, there are
users who want to have an EM (for thermal management for example), but
don't want EAS with it.

In order to let users disable EAS explicitly, introduce a new sysctl
called 'sched_energy_aware'. It is enabled by default so that EAS can
start automatically on platforms where it makes sense. Flipping it to 0
rebuilds the scheduling domains and disables EAS.

Signed-off-by: Quentin Perret <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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kernel/hung_task.c: allow to set checking interval separately from timeout

Currently task hung checking interval is equal to timeout, as the result
hung is detected anywhere between timeout and 2*ti

kernel/hung_task.c: allow to set checking interval separately from timeout

Currently task hung checking interval is equal to timeout, as the result
hung is detected anywhere between timeout and 2*timeout. This is fine for
most interactive environments, but this hurts automated testing setups
(syzbot). In an automated setup we need to strictly order CPU lockup <
RCU stall < workqueue lockup < task hung < silent loss, so that RCU stall
is not detected as task hung and task hung is not detected as silent
machine loss. The large variance in task hung detection timeout requires
setting silent machine loss timeout to a very large value (e.g. if task
hung is 3 mins, then silent loss need to be set to ~7 mins). The
additional 3 minutes significantly reduce testing efficiency because
usually we crash kernel within a minute, and this can add hours to bug
localization process as it needs to do dozens of tests.

Allow setting checking interval separately from timeout. This allows to
set timeout to, say, 3 minutes, but checking interval to 10 secs.

The interval is controlled via a new hung_task_check_interval_secs sysctl,
similar to the existing hung_task_timeout_secs sysctl. The default value
of 0 results in the current behavior: checking interval is equal to
timeout.

[[email protected]: update hung_task_timeout_max's comment]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Dmitry Vyukov <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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sched/sysctl: Remove unused sched_time_avg_ms sysctl

/proc/sys/kernel/sched_time_avg_ms entry is not used anywhere,
remove it.

Signed-off-by: Vincent Guittot <[email protected]>
Signed-off

sched/sysctl: Remove unused sched_time_avg_ms sysctl

/proc/sys/kernel/sched_time_avg_ms entry is not used anywhere,
remove it.

Signed-off-by: Vincent Guittot <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Luis R. Rodriguez <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: [email protected]
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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