Em Thu, Aug 20, 2015 at 11:16:32AM -0400, Dean Nelson escreveu:
> Running the following perf-stat command on an arm64 system produces the
> following result...
> [root@aarch64 ~]# perf stat -e kmem:mm_page_alloc -a sleep 1
> Warning: [kmem:mm_page_alloc] function sizeof not defined
> Warning: Error: expected type 4 but read 0
> Segmentation fault
> [root@aarch64 ~]#
Jiri, while testing this I noticed that when running as !root I get:
$ perf stat -e kmem:mm_page_alloc -a sleep 1
event syntax error: 'kmem:mm_page_alloc'
\___ unknown tracepoint
Run 'perf list' for a list of valid events
usage: perf stat [<options>] [<command>]
-e, --event <event> event selector. use 'perf list' to list available
events
[acme@zoo linux]$
Which could be a bit more friendly if it noticed that it may be a
tracepoint event and that if that is the case, the user needs to have
tracefs remounted with suitable permissions to be able to use
tracepoints, something like 'perf trace' does:
[acme@zoo linux]$ trace ls
Error: No permissions to read
/sys/kernel/debug/tracing/events/raw_syscalls/sys_(enter|exit)
Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'
[acme@zoo linux]$
Take that as a suggestion as you're more familiar with the event parsing
code :-)
- Arnaldo
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