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Groups > linux.kernel > #1213933
| From | Alexey Brodkin <Alexey.Brodkin@synopsys.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [arc-linux-dev] Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts |
| Date | 2015-08-26 16:50 +0200 |
| Message-ID | <q1Kbv-fe-9@gated-at.bofh.it> (permalink) |
| References | <q10V3-1Sr-3@gated-at.bofh.it> <q10V5-1Sr-31@gated-at.bofh.it> <q1ICK-6BL-23@gated-at.bofh.it> <q1IMq-6N8-25@gated-at.bofh.it> <q1K1P-8vu-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Hi Peter, On Wed, 2015-08-26 at 16:35 +-0200, Peter Zijlstra wrote: +AD4- On Wed, Aug 26, 2015 at 01:17:20PM +-0000, Alexey Brodkin wrote: +AD4- +AD4- Hi Peter, +AD4- +AD4- +AD4- +AD4- On Wed, 2015-08-26 at 15:07 +-0200, Peter Zijlstra wrote: +AD4- +AD4- +AD4- On Mon, Aug 24, 2015 at 05:20:20PM +-0300, Alexey Brodkin wrote: +AD4- +AD4- +AD4- +AD4- +AEAAQA- -139,9 +-141,11 +AEAAQA- static int arc+AF8-pmu+AF8-event+AF8-init(struct perf+AF8-event +ACo-event) +AD4- +AD4- +AD4- +AD4- struct hw+AF8-perf+AF8-event +ACo-hwc +AD0- +ACY-event-+AD4-hw+ADs- +AD4- +AD4- +AD4- +AD4- int ret+ADs- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- - hwc-+AD4-sample+AF8-period +AD0- arc+AF8-pmu-+AD4-max+AF8-period+ADs- +AD4- +AD4- +AD4- +AD4- - hwc-+AD4-last+AF8-period +AD0- hwc-+AD4-sample+AF8-period+ADs- +AD4- +AD4- +AD4- +AD4- - local64+AF8-set(+ACY-hwc-+AD4-period+AF8-left, hwc-+AD4-sample+AF8-period)+ADs- +AD4- +AD4- +AD4- +AD4- +- if (+ACE-is+AF8-sampling+AF8-event(event)) +AHs- +AD4- +AD4- +AD4- +AD4- +- hwc-+AD4-sample+AF8-period +AD0- arc+AF8-pmu-+AD4-max+AF8-period+ADs- +AD4- +AD4- +AD4- +AD4- +- hwc-+AD4-last+AF8-period +AD0- hwc-+AD4-sample+AF8-period+ADs- +AD4- +AD4- +AD4- +AD4- +- local64+AF8-set(+ACY-hwc-+AD4-period+AF8-left, hwc-+AD4-sample+AF8-period)+ADs- +AD4- +AD4- +AD4- +AD4- +- +AH0- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- So here we set a max+AF8-period sample period for +ACE-sampling events such that +AD4- +AD4- +AD4- we can properly deal with (short) counter overflow and accumulate into a +AD4- +AD4- +AD4- 64bit value. +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- switch (event-+AD4-attr.type) +AHs- +AD4- +AD4- +AD4- +AD4- case PERF+AF8-TYPE+AF8-HARDWARE: +AD4- +AD4- +AD4- +AD4- +AEAAQA- -243,6 +-247,11 +AEAAQA- static void arc+AF8-pmu+AF8-start(struct perf+AF8-event +ACo-event, int flags) +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- arc+AF8-pmu+AF8-event+AF8-set+AF8-period(event)+ADs- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +- /+ACo- Enable interrupt for this counter +ACo-/ +AD4- +AD4- +AD4- +AD4- +- if (is+AF8-sampling+AF8-event(event)) +AD4- +AD4- +AD4- +AD4- +- write+AF8-aux+AF8-reg(ARC+AF8-REG+AF8-PCT+AF8-INT+AF8-CTRL, +AD4- +AD4- +AD4- +AD4- +- read+AF8-aux+AF8-reg(ARC+AF8-REG+AF8-PCT+AF8-INT+AF8-CTRL) +AHw- (1 +ADwAPA- idx))+ADs- +AD4- +AD4- +AD4- +AD4- +- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- Yet here you fail to actually enable the interrupt for the non sampling +AD4- +AD4- +AD4- events, which makes the above not work. +AD4- +AD4- +AD4- +AD4- Indeed we intentionally leave interrupts disabled for non-sampling events. +AD4- +AD4- +AFs-1+AF0- We have quite large counters so we don't expect to overflow normally +AD4- +AD4- +AFs-2+AF0- We may re-use the same code for hardware that lacks support of IRQs in PCT. +AD4- +AD4- See we check if IRQs are available and if not set PERF+AF8-PMU+AF8-CAP+AF8-NO+AF8-INTERRUPT +AD4- +AD4- that will guarantee we won't get sampling event and for non-sampling events +AD4- +AD4- we won't use IRQs. +AD4- +AD4- Tricky, I was seeing is+AF8-isa+AF8-arcv2() calls elsewhere, so I figured you'd +AD4- make it conditional on that. +AD4- +AD4- But sure, if you think you can live with 1 this'll work. Well indeed there's a room for improvement always. But from our current experience existing implementation works pretty fine. Moreover having now PCT IRQs we mostly use sampling events that allow doing real profiling. -Alexey-- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH v3 0/6] ARCv2 port to Linux - (C) perf Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-24 16:30 +0200
[PATCH v3 6/6] ARCv2: perf: Finally introduce HS perf unit Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-24 16:30 +0200
[PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-24 16:30 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Peter Zijlstra <peterz@infradead.org> - 2015-08-26 15:10 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-26 15:20 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Peter Zijlstra <peterz@infradead.org> - 2015-08-26 16:40 +0200
Re: [arc-linux-dev] Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-26 16:50 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Peter Zijlstra <peterz@infradead.org> - 2015-08-26 15:20 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-26 15:30 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Peter Zijlstra <peterz@infradead.org> - 2015-08-26 16:40 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-26 16:40 +0200
Re: [PATCH v3 3/6] ARCv2: perf: Support sampling events using overflow interrupts Peter Zijlstra <peterz@infradead.org> - 2015-08-26 16:30 +0200
[PATCH v3 5/6] ARCv2: perf: SMP support Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-24 16:30 +0200
[PATCH v3 2/6] ARCv2: perf: implement "event_set_period" Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-24 16:30 +0200
Re: [PATCH v3 0/6] ARCv2 port to Linux - (C) perf Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-26 14:10 +0200
Re: [arc-linux-dev] Re: [PATCH v3 0/6] ARCv2 port to Linux - (C) perf Alexey Brodkin <Alexey.Brodkin@synopsys.com> - 2015-08-27 09:00 +0200
Re: [arc-linux-dev] Re: [PATCH v3 0/6] ARCv2 port to Linux - (C) perf Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2015-08-27 09:20 +0200
Re: [arc-linux-dev] Re: [PATCH v3 0/6] ARCv2 port to Linux - (C) perf Peter Zijlstra <peterz@infradead.org> - 2015-08-27 11:20 +0200
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