Messages in this thread | | | Subject | Re: perf: [patch] regression with PERF_EVENT_IOC_REFRESH | From | Peter Zijlstra <> | Date | Tue, 31 May 2011 09:23:13 +0200 |
| |
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.
| |