lkml.org 
[lkml]   [2009]   [Sep]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] perf_counter: cleanup for __perf_event_sched_in()


Paul Mackerras wrote:
> Xiao Guangrong writes:
>
>> It must be a group leader if event->attr.pinned is "1"
>
> Actually, looking at this more closely, it has to be a group leader
> anyway since it's at the top level of ctx->group_list. In fact I see
> four places where we do:
>
> list_for_each_entry(event, &ctx->group_list, group_entry) {
> if (event == event->group_leader)
> ...
>
> or the equivalent, three of which appear to have been introduced by
> afedadf2 ("perf_counter: Optimize sched in/out of counters") back in
> May by Peter Z.
>

I only find three places in __perf_event_sched_in/out, could you tell me
where is the fourth place?

I also noticed that all group leader is the top level of ctx->group_list,
if I not missed, the perf_event_init_task() function can be optimized,
like this:

int perf_event_init_task(struct task_struct *child)
{
......
/* We can only look at parent_ctx->group_list to get group leader */
list_for_each_entry_rcu(event, &parent_ctx->event_list, event_entry) {
if (event != event->group_leader)
continue;
......
}
......
}

I'll fix those if you are not mind :-)

Thanks,
Xiao


\
 
 \ /
  Last update: 2009-09-23 04:49    [W:1.239 / U:1.520 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site