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  1. 11 Aug, 2008 3 commits
    • Dmitry Adamushko's avatar
      sched, cpu hotplug: fix set_cpus_allowed() use in hotplug callbacks · 279ef6bb
      Dmitry Adamushko authored 
      Mark Langsdorf reported:

> One of my co-workers noticed that the powernow-k8
> driver no longer restarts when a CPU core is
> hot-disabled and then hot-enabled on AMD quad-core
> systems.
>
> The following comands work fine on 2.6.26 and fail
> on 2.6.27-rc1:
>
> echo 0 > /sys/devices/system/cpu/cpu3/online
> echo 1 > /sys/devices/system/cpu/cpu3/online
> find /sys -name cpufreq
>
> For 2.6.26, the find will return a cpufreq
> directory for each processor.  In 2.6.27-rc1,
> the cpu3 directory is missing.
>
> After digging through the code, the following
> logic is failing when the core is hot-enabled
> at runtime.  The code works during the boot
> sequence.
>
>       cpumask_t = current->cpus_allowed;
>       set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
>       if (smp_processor_id() != cpu)
>               return -ENODEV;

So set the CPU active before calling the CPU_ONLINE notifier chain,
there are a handful of notifiers that use set_cpus_allowed().

This fix also solves the problem with x86-microcode. I've sent
alternative patches for microcode, but as this "rely on
set_cpus_allowed_ptr() being workable in cpu-hotplug(CPU_ONLINE, ...)"
assumption seems to be more broad than what we thought, perhaps this fix
should be applied.

With this patch we define that by the moment CPU_ONLINE is being sent,
a 'cpu' is online and ready for tasks to be migrated onto it.
Signed-off-by: default avatarDmitry Adamushko <dmitry.adamushko@gmail.com>
Reported-by: default avatarMark Langsdorf <mark.langsdorf@amd.com>
Tested-by: default avatarMark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      279ef6bb
    • Mike Galbraith's avatar
      sched: fix mysql+oltp regression · 77ae6513
      Mike Galbraith authored 
      Defer commit 6d299f1b to the next release.

Testing of the tip/sched/clock tree revealed a mysql+oltp regression
which bisection eventually traced back to this commit in mainline.

Pertinent test results:  Three run sysbench averages, throughput units
in read/write requests/sec.

clients         1     2     4     8    16    32    64
6e0534f2      9646 17876 34774 33868 32230 30767 29441
2.6.26.1     9112 17936 34652 33383 31929 30665 29232
6d299f1b      9112 14637 28370 33339 32038 30762 29204

Note: subsequent commits hide the majority of this regression until you
apply the clock fixes, at which time it reemerges at full magnitude.

We cannot see anything bad about the change itself so we defer it to the
next release until this problem is fully analysed.
Signed-off-by: default avatarMike Galbraith <efault@gmx.de>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      77ae6513
    • Ingo Molnar's avatar
      Merge branch 'linus' into sched/urgent · 251a169c
      Ingo Molnar authored
      251a169c
  3. 08 Aug, 2008 37 commits
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