On Mon, 2010-02-08 at 17:06 +0200, Stephane Eranian wrote: > In certain situations, the kernel may need to stop and start the > same event rapidly. The current PMU callbacks do not distinguish > between stop and release (i.e., stop + free the resource). Thus, > a counter may be released, then it will be immediately re-acquired. > Event scheduling will again take place with no guarantee to assign > the same counter. On some processors, this may event yield to failure > to assign the event back due to competion between cores. > > This patch is adding a new pair of callback to stop and restart a > counter without actually release the underlying counter resource. > On stop, the counter is stopped, its values saved and that's it. > On start, the value is reloaded and counter is restarted (on x86, > actual restart is delayed until perf_enable()). > > Note this patch does not provide support for non-X86 PMU. This needs > to be added. > > Signed-off-by: Stephane Eranian <eran...@google.com> > --
I think we can do this much easier by adding a list_head to hw_perf_event and make event_list into a proper list, then we can remove that funny loop on remove and instead move the event to a remove_list when there's a put_event_constraint() method and iterate that list on hw_perf_enable(). But before we do that, I think we need to look at the /* hardware */ part of struct hw_perf_event, and make that arch specific, we've been growing that a lot lately and I don't think !x86 uses any of that. ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
