History log of /linux-6.15/tools/tracing/rtla/src/timerlat_u.c (Results 1 – 2 of 2)
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# e8c44d3b 15-Sep-2023 Daniel Bristot de Oliveira <[email protected]>

rtla/timerlat: Do not stop user-space if a cpu is offline

If no CPU list is passed, timerlat in user-space will dispatch
one thread per sysconf(_SC_NPROCESSORS_CONF). However, not all
CPU might be a

rtla/timerlat: Do not stop user-space if a cpu is offline

If no CPU list is passed, timerlat in user-space will dispatch
one thread per sysconf(_SC_NPROCESSORS_CONF). However, not all
CPU might be available, for instance, if HT is disabled.

Currently, rtla timerlat is stopping the session if an user-space
thread cannot set affinity to a CPU, or if a running user-space
thread is killed. However, this is too restrictive.

So, reduce the error to a debug message, and rtla timerlat run as
long as there is at least one user-space thread alive.

Link: https://lore.kernel.org/lkml/59cf2c882900ab7de91c6ee33b382ac7fa6b4ed0.1694781909.git.bristot@kernel.org

Fixes: cdca4f4e5e8e ("rtla/timerlat_top: Add timerlat user-space support")
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>

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Revision tags: v6.6-rc1, v6.5, v6.5-rc7, v6.5-rc6, v6.5-rc5, v6.5-rc4, v6.5-rc3, v6.5-rc2, v6.5-rc1, v6.4, v6.4-rc7, v6.4-rc6
# cdca4f4e 06-Jun-2023 Daniel Bristot de Oliveira <[email protected]>

rtla/timerlat_top: Add timerlat user-space support

Add the support for running timerlat threads in user-space. In this
mode, enabled with -u/--user-threads, timerlat dispatches user-space
processes

rtla/timerlat_top: Add timerlat user-space support

Add the support for running timerlat threads in user-space. In this
mode, enabled with -u/--user-threads, timerlat dispatches user-space
processes that will loop in the timerlat_fd, measuring the overhead
for going to user-space and then returning to the kernel - in addition
to the existing measurements.

Here is one example of the tool's output with -u enabled:

$ sudo timerlat top -u -d 600 -q
Timer Latency
0 00:10:01 | IRQ Timer Latency (us) | Thread Timer Latency (us) | Ret user Timer Latency (us)
CPU COUNT | cur min avg max | cur min avg max | cur min avg max
0 #600001 | 0 0 0 3 | 2 1 2 9 | 3 2 3 15
1 #600001 | 0 0 0 2 | 2 1 2 13 | 2 2 3 18
2 #600001 | 0 0 0 10 | 2 1 2 16 | 3 2 3 20
3 #600001 | 0 0 0 7 | 2 1 2 10 | 3 2 3 11
4 #600000 | 0 0 0 16 | 2 1 2 41 | 3 2 3 58
5 #600000 | 0 0 0 3 | 2 1 2 10 | 3 2 3 13
6 #600000 | 0 0 0 5 | 2 1 2 7 | 3 2 3 10
7 #600000 | 0 0 0 1 | 2 1 2 7 | 3 2 3 10

The tuning setup like -p or -C work for the user-space threads as well.

Link: https://lkml.kernel.org/r/758ad2292a0a1d884138d08219e1a0f572d257a2.1686066600.git.bristot@kernel.org

Cc: William White <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Tested-by: Juri Lelli <[email protected]>
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

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