Re: [PATCH 09/14] perf ftrace: Add 'record' sub-command

[David Ahern]

On 5/5/13 7:57 PM, Namhyung Kim wrote:
> Hi David,
>
> On Fri, 26 Apr 2013 07:44:18 -0600, David Ahern wrote:
> > On 4/25/13 12:24 AM, Namhyung Kim wrote:
> > > But it looks there's a race between cond_wait() and cond_broatcast().
> > > I'll take a look at that.
> >
> > Why not use eventfd or a pipe for the signalling instead?
>
> Thanks for your feedback!
>
> I didn't have an idea of using eventfd for this case.  Does it helpful
> to prevent such a deadlock like this?

I have used it to replace pthread_cond_wait / 
pthread_cond_{signal,broadcast} -- lighter and faster. It was added in 
2.6.27 I believe, so will be available for any system that supports perf 
(record side). For people compiling perf against say RHEL5 (e.g. 
analysis) you will need a check as to whether it exists.

David

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