Re: perf: [patch] regression with PERF_EVENT_IOC_REFRESH

[Peter Zijlstra]

On Mon, 2011-05-30 at 21:33 -0400, Vince Weaver wrote:
> the problem was the mentioned commit tried to optimize the use of 
> watermark and wakeup_watermark without taking into account that 
> wakeup_watermark is a union with wakeup_events. 

Note that wake_events isn't related to IOC_REFRESH, wake_events is how
much events to buffer in the mmap-buffer before issuing a wakeup.

IOC_REFRESH increments event_limit, which is how many events to run
before disabling yourself.

What I gather is that due to that SIGIO bug (fixed by f506b3dc0e), you
had to have both an mmap and a wakeup in order for that signal to
arrive.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/