Hi,
On Mon, Apr 26, 2010 at 9:59 AM, Zhang, Yanmin
<yanmin_zhang@xxxxxxxxxxxxxxx> wrote:
>>>> I haven't been able to reproduce this either on my Core 2 machine.
>>> Mostly, the regression exists on Nehalem machines. I suspect it's related to
>>> hyper-threading machine.
On 04/26/2010 09:22 AM, Pekka Enberg wrote:
>> OK, so does anyone know why hyper-threading would change things for
>> the per-CPU allocator?
On Mon, Apr 26, 2010 at 1:02 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> My wild speculation is that previously the cpu_slub structures of two
> neighboring threads ended up on the same cacheline by accident thanks
> to the back to back allocation. W/ the percpu allocator, this no
> longer would happen as the allocator groups percpu data together
> per-cpu.
Yanmin, do we see a lot of remote frees for your hackbench run? IIRC,
it's the "deactivate_remote_frees" stat when CONFIG_SLAB_STATS is
enabled.
Pekka
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