Messages in this thread | | | From | Jirka Hladky <> | Date | Wed, 22 Jun 2016 10:25:19 +0200 | Subject | Re: Kernel 4.7rc3 - Performance drop 30-40% for SPECjbb2005 and SPECjvm2008 benchmarks against 4.6 kernel |
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Hi Branimir,
I don't think that it's related. The regression has happened in one of these two commits:
$ git log --pretty=oneline e7904a28f5331c21d17af638cb477c83662e3cb6..6ecdd74962f246dfe8750b7bea481a1c0816315d 6ecdd74962f246dfe8750b7bea481a1c0816315d sched/fair: Generalize the load/util averages resolution definition 2159197d66770ec01f75c93fb11dc66df81fd45b sched/core: Enable increased load resolution on 64-bit kernels
Please see https://bugzilla.kernel.org/show_bug.cgi?id=120481 for the details.
Jirka
On Wed, Jun 22, 2016 at 9:37 AM, Branimir Maksimovic <branimir.maksimovic@gmail.com> wrote: > Could it be related to this: > > https://www.phoronix.com/scan.php?page=news_item&px=P-State-Possible-4.6-Regression > > > On Thu, 16 Jun 2016 18:40:01 +0200 > Jirka Hladky <jhladky@redhat.com> wrote: > >> Hello, >> >> we see performance drop 30-40% for SPECjbb2005 and SPECjvm2008 >> benchmarks starting from 4.7.0-0.rc0 kernel compared to 4.6 kernel. >> >> We have tested kernels 4.7.0-0.rc1 and 4.7.0-0.rc3 and these are as >> well affected. >> >> We have observed the drop on variety of different x86_64 servers with >> different configuration (different CPU models, RAM sizes, both with >> Hyper Threading ON and OFF, different NUMA configurations (2 and 4 >> NUMA nodes) >> >> Linpack and Stream benchmarks do not show any performance drop. >> >> The performance drop increases with higher number of threads. The >> maximum number of threads in each benchmark is the same as number of >> CPUs. >> >> We have opened a BZ to track the progress: >> https://bugzilla.kernel.org/show_bug.cgi?id=120481 >> >> You can find more details along with graphs and tables there. >> >> Do you have any hints which commit should we try to reverse? >> >> Thanks a lot! >> Jirka >
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