Messages in this thread | | | From | Stephane Eranian <> | Date | Fri, 19 Jan 2018 09:55:11 -0800 | Subject | Re: [PATCH V5 4/8] perf/x86/intel/uncore: add new data structures for free running counters |
| |
On Fri, Jan 19, 2018 at 9:53 AM, Liang, Kan <kan.liang@intel.com> wrote: >> On Fri, Jan 19, 2018 at 03:15:00PM +0000, Liang, Kan wrote: >> > > >> > > On Thu, Jan 18, 2018 at 05:43:10PM +0000, Liang, Kan wrote: >> > > > In the uncore document, there is no event-code assigned to free >> > > > running >> > > counters. >> > > > Some events need to be defined to indicate the free running counters. >> > > > The events are encoded as event-code + umask-code. >> > > > >> > > > The event-code for all free running counters is 0xff, which is the >> > > > same as the fixed counters. >> > > >> > > Is it possible to count the same things using the generic counters? >> > > >> > >> > Yes, there are events for generic counters to count bandwidth and >> > utilization. >> > >> > The reasons of introducing free running counters are >> > - To provide highly valuable information (bandwidth and utilization) >> > which most of the customers are interested in >> > - To save on the precious generic counters >> >> _IF_ the exact same counters are available on the GPs then we must use the >> same event code for them and use event scheduling to place them on >> fixed/free-running counters when possible. > > OK. I will check if there are the exact same events on GPs for > those free running counters. > You can measure the bandwidth and utilization on the GP. I am doing it all the time.
> Thanks, > Kan > >> >> That's what we do for the CPU PMU's fixed counters too. >> >> Don't invent magic event codes just because.
| |