Messages in this thread | | | Date | Wed, 3 Aug 2022 11:51:14 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCHSET 0/6] perf lock: Add contention subcommand (v1) |
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* Namhyung Kim <namhyung@kernel.org> wrote:
> Hello, > > It's to add a new subcommand 'contention' (shortly 'con') to perf lock. > > The new subcommand is to handle the new lock:contention_{begin,end} > tracepoints and shows lock type and caller address like below: > > $ perf lock contention > contended total wait max wait avg wait type caller > > 238 1.41 ms 29.20 us 5.94 us spinlock update_blocked_averages+0x4c > 1 902.08 us 902.08 us 902.08 us rwsem:R do_user_addr_fault+0x1dd > 81 330.30 us 17.24 us 4.08 us spinlock _nohz_idle_balance+0x172 > 2 89.54 us 61.26 us 44.77 us spinlock do_anonymous_page+0x16d > 24 78.36 us 12.27 us 3.27 us mutex pipe_read+0x56 > 2 71.58 us 59.56 us 35.79 us spinlock __handle_mm_fault+0x6aa > 6 25.68 us 6.89 us 4.28 us spinlock do_idle+0x28d > 1 18.46 us 18.46 us 18.46 us rtmutex exec_fw_cmd+0x21b > 3 15.25 us 6.26 us 5.08 us spinlock tick_do_update_jiffies64+0x2c > ...
Wouldn't it also be useful to display a lock contention percentage value, the ratio of fastpath vs. contended/wait events?
That's usually the first-approximation metric to see how contended different locks are, and the average wait time quantifies it.
Thanks,
Ingo
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