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SubjectRe: [PATCH] Cgroup: Fix memory accounting scalability in shrink_page_list
On Thu, Jul 19, 2012 at 04:34:26PM -0700, Tim Chen wrote:
> Hi,
>
> I noticed in a multi-process parallel files reading benchmark I ran on a
> 8 socket machine, throughput slowed down by a factor of 8 when I ran
> the benchmark within a cgroup container. I traced the problem to the
> following code path (see below) when we are trying to reclaim memory
> from file cache. The res_counter_uncharge function is called on every
> page that's reclaimed and created heavy lock contention. The patch
> below allows the reclaimed pages to be uncharged from the resource
> counter in batch and recovered the regression.
>
> Tim
>
> 40.67% usemem [kernel.kallsyms] [k] _raw_spin_lock
> |
> --- _raw_spin_lock
> |
> |--92.61%-- res_counter_uncharge
> | |
> | |--100.00%-- __mem_cgroup_uncharge_common
> | | |
> | | |--100.00%-- mem_cgroup_uncharge_cache_page
> | | | __remove_mapping
> | | | shrink_page_list
> | | | shrink_inactive_list
> | | | shrink_mem_cgroup_zone
> | | | shrink_zone
> | | | do_try_to_free_pages
> | | | try_to_free_pages
> | | | __alloc_pages_nodemask
> | | | alloc_pages_current
>
>
> ---
> Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

--
Kirill A. Shutemov
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