On Fri, Apr 17, 2015 at 12:50:33PM +0000, Liang, Kan wrote: > > > > > > > > A) the CTRn value reaches 0: > > > - the corresponding bit in GLOBAL_STATUS gets set > > > - we start arming the hardware assist > > > > > > < some unspecified amount of time later -- > > > this could cover multiple events of interest > > > > > > > B) the hardware assist is armed, any next event will trigger it > > > > > > C) a matching event happens: > > > - the hardware assist triggers and generates a PEBS record > > > this includes a copy of GLOBAL_STATUS at this moment > > > - if we auto-reload we (re)set CTRn > > > > Is this actually true? Do we reload here or on A ? > > > > Yes, on C. > According to SDM Volume 3, 18.7.1.1, the reset value will be > loaded after each PEBS record is written, which is done > by hw assist.
OK, then I did indeed remember that right. But that brings us to patch 1 of this series, how is that correct in the face of this? There is an arbitrary delay (A->B) added to the period. And the Changelog of course never did bother to make that clear. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
