Messages in this thread | | | From | "Liang, Kan" <> | Subject | RE: [PATCH V6 4/6] perf, x86: handle multiple records in PEBS buffer | Date | Fri, 17 Apr 2015 12:50:33 +0000 |
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> > > > 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.
> > - we clear the relevant bit in GLOBAL_STATUS
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