linux-arm.git - Russell King's ARM Linux kernel tree

Age	Commit message (Collapse)	Author
2023-09-22	rtla/timerlat: Do not stop user-space if a cpu is offline	Daniel Bristot de Oliveira
	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 <bristot@kernel.org>
2023-06-13	rtla/timerlat_top: Add timerlat user-space support	Daniel Bristot de Oliveira
	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 <chwhite@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Tested-by: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>