* David Rientjes <rientjes@xxxxxxxxxx> wrote:
> > numa/core at ec05a2311c35 ("Merge branch 'sched/urgent' into
> > sched/core") had an average throughput of 136918.34
> > SPECjbb2005 bops, which is a 6.3% regression.
>
> perftop during the run on numa/core at 01aa90068b12 ("sched:
> Use the best-buddy 'ideal cpu' in balancing decisions"):
>
> 15.99% [kernel] [k] page_fault
> 4.05% [kernel] [k] getnstimeofday
> 3.96% [kernel] [k] _raw_spin_lock
> 3.20% [kernel] [k] rcu_check_callbacks
> 2.93% [kernel] [k] generic_smp_call_function_interrupt
> 2.90% [kernel] [k] __do_page_fault
> 2.82% [kernel] [k] ktime_get
Thanks for testing, that's very interesting - could you tell me
more about exactly what kind of hardware this is? I'll try to
find a similar system and reproduce the performance regression.
(A wild guess would be an older 4x Opteron system, 83xx series
or so?)
Also, the profile looks weird to me. Here is how perf top looks
like on my system during a similarly configured, "healthy"
SPECjbb run:
91.29% perf-6687.map [.] 0x00007fffed1e8f21
4.81% libjvm.so [.] 0x00000000007004a0
0.93% [vdso] [.] 0x00007ffff7ffe60c
0.72% [kernel] [k] do_raw_spin_lock
0.36% [kernel] [k] generic_smp_call_function_interrupt
0.10% [kernel] [k] format_decode
0.07% [kernel] [k] rcu_check_callbacks
0.07% [kernel] [k] apic_timer_interrupt
0.07% [kernel] [k] call_function_interrupt
0.06% libc-2.15.so [.] __strcmp_sse42
0.06% [kernel] [k] irqtime_account_irq
0.06% perf [.] 0x000000000004bb7c
0.05% [kernel] [k] x86_pmu_disable_all
0.04% libc-2.15.so [.] __memcpy_ssse3
0.04% [kernel] [k] ktime_get
0.04% [kernel] [k] account_group_user_time
0.03% [kernel] [k] vbin_printf
and that is what SPECjbb does: it spends 97% of its time in Java
code - yet there's no Java overhead visible in your profile -
how is that possible? Could you try a newer perf on that box:
cd tools/perf/
make -j install
to make sure perf picks up the Java symbols as well (or at least
includes them as a summary, as in the profile above). Note that
no page fault overhead is visible in my profile.
Thanks,
Ingo
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