Daniel Wagner reported to me that readproc.h got deprecated. Also,
while the procps-ng library was available on Fedora, it was not available
on RHEL, which is a piece of evidence that it was not that used.
rtla uses procps-ng only to find the PID of the tracers' workload.
I used the procps-ng library to avoid reinventing the wheel. But in this
case, reinventing the wheel took me less time than the time we already
took trying to work around problems.
Implement a function that reads /proc/ entries, checking if:
- the entry is a directory
- the directory name is composed only of digits (PID)
- the directory contains the comm file
- the comm file contains a comm that matches the tracers'
workload prefix.
- then return true; otherwise, return false.
And use it instead of procps-ng.
Link: https://lkml.kernel.org/r/e8276e122ee9eb2c5a0ba8e673fb6488b924b825.1652423574.git.bristot@kernel.org
Cc: John Kacur <jkacur@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tao Zhou <tao.zhou@linux.dev>
Fixes: b1696371d8 ("rtla: Helper functions for rtla")
Reported-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
$(or ...) is available since GNU Make 3.81, and useful to shorten the
code in some places.
Covert as follows:
$(if A,A,B) --> $(or A,B)
This patch also converts:
$(if A, A, B) --> $(or A, B)
Strictly speaking, the latter is not an equivalent conversion because
GNU Make keeps spaces after commas; if A is not empty, $(if A, A, B)
expands to " A", while $(or A, B) expands to "A".
Anyway, preceding spaces are not significant in the code hunks I touched.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
The rtla timerlat tool is an interface for the timerlat tracer.
The timerlat tracer dispatches a kernel thread per-cpu. These threads set a
periodic timer to wake themselves up and go back to sleep. After the
wakeup, they collect and generate useful information for the debugging of
operating system timer latency.
The timerlat tracer outputs information in two ways. It periodically
prints the timer latency at the timer IRQ handler and the Thread handler.
It also provides information for each noise via the osnoise tracepoints.
The rtla timerlat top mode displays a summary of the periodic output from
the timerlat tracer.
Here is one example of the rtla timerlat tool output:
---------- %< ----------
[root@alien ~]# rtla timerlat top -c 0-3 -d 1m
Timer Latency
0 00:01:00 | IRQ Timer Latency (us) | Thread Timer Latency (us)
CPU COUNT | cur min avg max | cur min avg max
0 #60001 | 0 0 0 3 | 1 1 1 6
1 #60001 | 0 0 0 3 | 2 1 1 5
2 #60001 | 0 0 1 6 | 1 1 2 7
3 #60001 | 0 0 0 7 | 1 1 1 11
---------- >% ----------
Running:
# rtla timerlat --help
# rtla timerlat top --help
provides information about the available options.
Link: https://lkml.kernel.org/r/e95032e20c2b88c962195bf7693bb53c9ebcced8.1639158831.git.bristot@kernel.org
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: linux-rt-users@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
