Re: [PATCH 1/2] perf test: Silence tracepoint event failures

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Oct 20, 2015 at 12:23:48AM +0900, Namhyung Kim escreveu:
> Currently, when perf test is run by a normal user, it'll fail to access
> tracepoint events.  However the output is somewhat messy since it tries
> to be nice with long error messages and hints.  IMHO it's not needed
> for 'perf test' by default and AFAIK the perf test uses pr_debug()
> rather than pr_err() for such messages so that one can use -v option to
> see further details on failed testcases if needed.
> 
> Before:
>   $ perf test
>    1: vmlinux symtab matches kallsyms                          : FAILED!
>    2: detect openat syscall event                              :Error:
>   No permissions to read
>   /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat
>   Hint:	Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
>   FAILED!
>    3: detect openat syscall event on all cpus                  :Error:
>   No permissions to read
>   /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat
>   Hint:	Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
>   FAILED!
>    ...
> 
> After:
>   $ perf test
>    1: vmlinux symtab matches kallsyms                          : FAILED!
>    2: detect openat syscall event                              : FAILED!
>    3: detect openat syscall event on all cpus                  : FAILED!
>    ...
> 
>   $ perf test -v 2
>    2: detect openat syscall event                              :
>   --- start ---
>   test child forked, pid 30575
>   Error:	    No permissions to read
>   /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat
>   Hint:  Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
> 
>   test child finished with -1
>   ---- end ----
>   detect openat syscall event: FAILED!


Here I get useless informational messages about registering plugins,
guess those should move to pr_debug2, no?

Anyway, applying the patch, the common case is to run 'perf test'.


[acme@zoo linux]$ perf test -v 2
 2: detect openat syscall event                              :
--- start ---
test child forked, pid 22866
registering plugin: /home/acme/.traceevent/plugins/plugin_function.so
registering plugin: /home/acme/.traceevent/plugins/plugin_mac80211.so
registering plugin: /home/acme/.traceevent/plugins/plugin_scsi.so
registering plugin: /home/acme/.traceevent/plugins/plugin_hrtimer.so
registering plugin: /home/acme/.traceevent/plugins/plugin_sched_switch.so
registering plugin: /home/acme/.traceevent/plugins/plugin_cfg80211.so
registering plugin: /home/acme/.traceevent/plugins/plugin_kmem.so
registering plugin: /home/acme/.traceevent/plugins/plugin_kvm.so
registering plugin: /home/acme/.traceevent/plugins/plugin_xen.so
registering plugin: /home/acme/.traceevent/plugins/plugin_jbd2.so
Error:	No permissions to read /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat
Hint:	Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'

test child finished with -1
---- end ----
detect openat syscall event: FAILED!
[acme@zoo linux]$