The enhancements made to timerlat_load.py are intended to improve the script's exception handling.
Summary of the changes:
- Specific exceptions are now caught for CPU affinity and priority
settings, with clearer error messages provided.
- The timerlat file descriptor opening now includes handling for
PermissionError and OSError, with informative messages.
- In the infinite loop, generic exceptions have been replaced with
specific types like KeyboardInterrupt and IOError, improving feedback.
Before:
$ sudo python timerlat_load.py 122
Error setting affinity
After:
$ sudo python timerlat_load.py 122
Error setting affinity: [Errno 22] Invalid argument
Before:
$ sudo python timerlat_load.py 1 -p 950
Error setting priority
After:
$ sudo python timerlat_load.py 1 -p 950
Error setting priority: [Errno 22] Invalid argument
Before:
$ python timerlat_load.py 1
Error opening timerlat fd, did you run timerlat -U?
After:
$ python timerlat_load.py 1
Permission denied. Please check your access rights.
Cc: "lgoncalv@redhat.com" <lgoncalv@redhat.com>
Cc: "jkacur@redhat.com" <jkacur@redhat.com>
Link: https://lore.kernel.org/Q_k1s4hBtUy2px8ou0QKenjEK2_T_LoV8IxAE79aBakBogb-7uHp2fpET3oWtI1t3dy8uKjWeRzQOdKNzIzOOpyM4OjutJOriZ9TrGY6b-g=@protonmail.com
Signed-off-by: Furkan Onder <furkanonder@protonmail.com>
Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The timerlat tracer provides an interface for any application to wait
for the timerlat's periodic wakeup. Currently, rtla timerlat uses it
to dispatch its user-space workload (-u option).
But as the tracer interface is generic, rtla timerlat can also be used
to monitor any workload that uses it. For example, a user might
place their own workload to wait on the tracer interface, and
monitor the results with rtla timerlat.
Add the -U option to rtla timerlat top and hist. With this option, rtla
timerlat will not dispatch its workload but only setting up the
system, waiting for a user to dispatch its workload.
The sample code in this patch is an example of python application
that loops in the timerlat tracer fd.
To use it, dispatch:
# rtla timerlat -U
In a terminal, then run the python program on another terminal,
specifying the CPU to run it. For example, setting on CPU 1:
#./timerlat_load.py 1
Then rtla timerlat will start printing the statistics of the
./timerlat_load.py app.
An interesting point is that the "Ret user Timer Latency" value
is the overall response time of the load. The sample load does
a memory copy to exemplify that.
The stop tracing options on rtla timerlat works in this setup
as well, including auto analysis.
Link: https://lkml.kernel.org/r/36e6bcf18fe15c7601048fd4c65aeb193c502cc8.1707229706.git.bristot@kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
