Messages in this thread | | | Date | Mon, 19 Jun 2017 16:14:41 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi |
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On Mon, Jun 19, 2017 at 04:37:41PM +0300, Alexey Budankov wrote: > On 19.06.2017 16:26, Mark Rutland wrote: > >On Mon, Jun 19, 2017 at 04:08:32PM +0300, Alexey Budankov wrote: > >>On 16.06.2017 1:10, Alexey Budankov wrote: > >>>On 15.06.2017 22:56, Mark Rutland wrote: > >>>>On Thu, Jun 15, 2017 at 08:41:42PM +0300, Alexey Budankov wrote: > >>>>>This series of patches continues v2 and addresses captured comments. > > > >>>>>Specifically this patch replaces pinned_groups and flexible_groups > >>>>>lists of perf_event_context by red-black cpu indexed trees avoiding > >>>>>data structures duplication and introducing possibility to iterate > >>>>>event groups for a specific CPU only. > > > >>>>Have you thrown Vince's perf fuzzer at this? > >>>> > >>>>If you haven't, please do. It can be found in the fuzzer directory of: > >>>> > >>>>https://github.com/deater/perf_event_tests > >>> > >>>Accepted. > >> > >>I run the test suite and it revealed no additional regressions in > >>comparison to what I have on the clean kernel. > >> > >>However the fuzzer constantly reports some strange stacks that are > >>not seen on the clean kernel and I have no idea how that might be > >>caused by the patches. > > > >Ok; that was the kind of thing I was concerned about. > > > >What you say "strange stacks", what do you mean exactly? > > > >I take it the kernel spewing backtraces in dmesg? > > > >Can you dump those? > > Here it is: > > list_del corruption. prev->next should be ffff88c2c4654010, but was > ffff88c31eb0c020 > [ 607.632813] ------------[ cut here ]------------ > [ 607.632816] kernel BUG at lib/list_debug.c:53!
> [ 607.635531] Call Trace: > [ 607.635583] list_del_event+0x1d7/0x210
Given this patch changes how list_{del,add}_event() works, it's possible that this is a new bug.
I was going to try to test this on arm64, but I couldn't get the patch to apply. I had a go with v4.12-rc5, tip/perf/core, and tip/perf/urgent.
Which branch should I be using as the base?
Thanks, Mark
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