Re: [PATCH v2 4/6] mm: Only IPI CPUs to drain local pages if theyexist

From: Rik van Riel
Date: Fri Oct 28 2011 - 12:08:09 EST


On 10/23/2011 11:56 AM, Gilad Ben-Yossef wrote:
Use a cpumask to track CPUs with per-cpu pages in any zone
and only send an IPI requesting CPUs to drain these pages
to the buddy allocator if they actually have pages.

+/* Which CPUs have per cpu pages */
+cpumask_var_t cpus_with_pcp;
+static DEFINE_PER_CPU(unsigned long, total_cpu_pcp_count);

Does the flushing happen so frequently that it is worth keeping this
state on a per-cpu basis, or would it be better to check each CPU's
pcp info and assemble a cpumask at flush time like done in patch 5?



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