Re: perf: PERF_FLAG_FD_OUTPUT has been broken since 2.6.35

From: Vince Weaver
Date: Fri Jan 09 2015 - 11:26:10 EST



On Fri, 9 Jan 2015, Peter Zijlstra wrote:
> > So is this worth fixing seeing as apparently no one uses this feature?
>
> I think there's a fair argument for removing it, Ingo, Acme?

could the functionality be replaced with a subsequent call to
ioctl(PERF_EVENT_IOC_SET_OUTPUT)
?

Although I suppose there's a possibility for losing a small amount of data
or some other reason that PERF_FLAG_FD_OUTPUT was introduced in the first
place.

In addition, if we remove PERF_FLAG_FD_OUTPUT would there then be any
reason to keep PERF_FLAG_FD_NO_GROUP around?

Vince
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