Messages in this thread | | | Date | Fri, 23 Aug 2019 15:03:23 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] perf cgroups: Don't rotate events for cgroups unnecessarily |
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On Fri, Aug 23, 2019 at 06:26:34PM +0530, Ganapatrao Kulkarni wrote: > On Fri, Aug 23, 2019 at 5:29 PM Peter Zijlstra <peterz@infradead.org> wrote: > > On Fri, Aug 23, 2019 at 04:13:46PM +0530, Ganapatrao Kulkarni wrote: > > > > > We are seeing regression with our uncore perf driver(Marvell's > > > ThunderX2, ARM64 server platform) on 5.3-Rc1. > > > After bisecting, it turned out to be this patch causing the issue. > > > > Funnily enough; the email you replied to didn't contain a patch. > > Hmm sorry, not sure why the patch is clipped-off, I see it in my inbox.
Your email is in a random spot of the discussion for me. At least it was fairly easy to find the related patch.
> > > Test case: > > > Load module and run perf for more than 4 events( we have 4 counters, > > > event multiplexing takes place for more than 4 events), then unload > > > module. > > > With this sequence of testing, the system hangs(soft lockup) after 2 > > > or 3 iterations. Same test runs for hours on 5.2. > > > > > > while [ 1 ] > > > do > > > rmmod thunderx2_pmu > > > modprobe thunderx2_pmu > > > perf stat -a -e \ > > > uncore_dmc_0/cnt_cycles/,\ > > > uncore_dmc_0/data_transfers/,\ > > > uncore_dmc_0/read_txns/,\ > > > uncore_dmc_0/config=0xE/,\ > > > uncore_dmc_0/write_txns/ sleep 1 > > > sleep 2 > > > done > > > > Can you reproduce without the module load+unload? I don't think people > > routinely unload modules. > > The issue wont happen, if module is not unloaded/reloaded. > IMHO, this could be potential bug!
Does the softlockup give a useful stacktrace? I don't have a thunderx2 so I cannot reproduce.
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