kernel: Fix "select" wording on HZ_250 description

HZ_250 config description contains alternative choice for NTSC
media users (HZ_300), which is written as "selected 300Hz". This is
incorrect, as it

kernel: Fix "select" wording on HZ_250 description

HZ_250 config description contains alternative choice for NTSC
media users (HZ_300), which is written as "selected 300Hz". This is
incorrect, as it implies that HZ_300 is automatically selected
whereas the user has chosen HZ_250 instead.

Fix the wording to "select 300Hz".

Signed-off-by: Bagas Sanjaya <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS

We've switched over every architecture that supports SMP to it, so
remove the new useless config variable.

Signed-off-by: Christoph Hellwig <[email protected]

kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS

We've switched over every architecture that supports SMP to it, so
remove the new useless config variable.

Signed-off-by: Christoph Hellwig <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

sched: fix SCHED_HRTICK dependency

Currently, it seems SCHED_HRTICK allowed for !SMP. But, it seems to have
no dependency of it. Fix it.

Signed-off-by: OGAWA Hirofumi <[email protected]>

sched: fix SCHED_HRTICK dependency

Currently, it seems SCHED_HRTICK allowed for !SMP. But, it seems to have
no dependency of it. Fix it.

Signed-off-by: OGAWA Hirofumi <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

sched: fix hrtick & generic-ipi dependency

Andrew Morton reported this s390 allmodconfig build failure:

kernel/built-in.o: In function `hrtick_start_fair':
sched.c:(.text+0x69c6): undefined refer

sched: fix hrtick & generic-ipi dependency

Andrew Morton reported this s390 allmodconfig build failure:

kernel/built-in.o: In function `hrtick_start_fair':
sched.c:(.text+0x69c6): undefined reference to `__smp_call_function_single'

the reason is that s390 is not a generic-ipi SMP platform yet, while
the hrtick code relies on it. Fix the dependency.

Signed-off-by: Ingo Molnar <[email protected]>

show more ...

sched, x86: clean up hrtick implementation

random uvesafb failures were reported against Gentoo:

http://bugs.gentoo.org/show_bug.cgi?id=222799

and Mihai Moldovan bisected it back to:

> 8f4d37ec

sched, x86: clean up hrtick implementation

random uvesafb failures were reported against Gentoo:

http://bugs.gentoo.org/show_bug.cgi?id=222799

and Mihai Moldovan bisected it back to:

> 8f4d37ec073c17e2d4aa8851df5837d798606d6f is first bad commit
> commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f
> Author: Peter Zijlstra <[email protected]>
> Date: Fri Jan 25 21:08:29 2008 +0100
>
> sched: high-res preemption tick

Linus suspected it to be hrtick + vm86 interaction and observed:

> Btw, Peter, Ingo: I think that commit is doing bad things. They aren't
> _incorrect_ per se, but they are definitely bad.
>
> Why?
>
> Using random _TIF_WORK_MASK flags is really impolite for doing
> "scheduling" work. There's a reason that arch/x86/kernel/entry_32.S
> special-cases the _TIF_NEED_RESCHED flag: we don't want to exit out of
> vm86 mode unnecessarily.
>
> See the "work_notifysig_v86" label, and how it does that
> "save_v86_state()" thing etc etc.

Right, I never liked having to fiddle with those TIF flags. Initially I
needed it because the hrtimer base lock could not nest in the rq lock.
That however is fixed these days.

Currently the only reason left to fiddle with the TIF flags is remote
wakeups. We cannot program a remote cpu's hrtimer. I've been thinking
about using the new and improved IPI function call stuff to implement
hrtimer_start_on().

However that does require that smp_call_function_single(.wait=0) works
from interrupt context - /me looks at the latest series from Jens - Yes
that does seem to be supported, good.

Here's a stab at cleaning this stuff up ...

Mihai reported test success as well.

Signed-off-by: Peter Zijlstra <[email protected]>
Tested-by: Mihai Moldovan <[email protected]>
Cc: Michal Januszewski <[email protected]>
Cc: Antonino Daplas <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

sched: high-res preemption tick

Use HR-timers (when available) to deliver an accurate preemption tick.

The regular scheduler tick that runs at 1/HZ can be too coarse when nice
level are used. The f

sched: high-res preemption tick

Use HR-timers (when available) to deliver an accurate preemption tick.

The regular scheduler tick that runs at 1/HZ can be too coarse when nice
level are used. The fairness system will still keep the cpu utilisation 'fair'
by then delaying the task that got an excessive amount of CPU time but try to
minimize this by delivering preemption points spot-on.

The average frequency of this extra interrupt is sched_latency / nr_latency.
Which need not be higher than 1/HZ, its just that the distribution within the
sched_latency period is important.

Signed-off-by: Peter Zijlstra <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

[PATCH] HZ: 300Hz support

Fix two things. Firstly the unit is "Hz" not "HZ". Secondly it is useful
to have 300Hz support when doing multimedia work. 250 is fine for us in
Europe but the US frame

[PATCH] HZ: 300Hz support

Fix two things. Firstly the unit is "Hz" not "HZ". Secondly it is useful
to have 300Hz support when doing multimedia work. 250 is fine for us in
Europe but the US frame rate is 30fps (29.99 blah for pedants). 300 gives
us a tick divisible by both 25 and 30, and for interlace work 50 and 60.
It's also giving similar performance to 250Hz.

I'd argue we should remove 250 and add 300, but that might be excess
disruption for now.

Signed-off-by: Alan Cox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

[PATCH] i386: Selectable Frequency of the Timer Interrupt

Make the timer frequency selectable. The timer interrupt may cause bus
and memory contention in large NUMA systems since the interrupt occur

[PATCH] i386: Selectable Frequency of the Timer Interrupt

Make the timer frequency selectable. The timer interrupt may cause bus
and memory contention in large NUMA systems since the interrupt occurs
on each processor HZ times per second.

Signed-off-by: Christoph Lameter <[email protected]>
Signed-off-by: Shai Fultheim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...