Re: [PATCH 2/3] mm: page allocator: Calculate a better estimate ofNR_FREE_PAGES when memory is low and kswapd is awake
From: Christoph Lameter
Date: Mon Aug 23 2010 - 08:56:51 EST
On Mon, 23 Aug 2010, Mel Gorman wrote:
> This patch introduces zone_nr_free_pages() to take a slightly more accurate
> estimate of NR_FREE_PAGES while kswapd is awake. The estimate is not perfect
> and may result in cache line bounces but is expected to be lighter than the
> IPI calls necessary to continually drain the per-cpu counters while kswapd
> is awake.
The delta of the counters could also be reduced to increase accuracy.
See refresh_zone_stat_thresholds().
Also would it be possible to add the summation function to vmstat? It may
be useful elsewhere.
A new function like
zone_page_state_snapshot()
or so?
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