From: Mel Gorman <mgorman@techsingularity.net> To: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, Minchan Kim <minchan@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@techsingularity.net> Subject: [PATCH 1/4] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit -fix Date: Wed, 13 Jul 2016 11:00:01 +0100 [thread overview] Message-ID: <1468404004-5085-2-git-send-email-mgorman@techsingularity.net> (raw) In-Reply-To: <1468404004-5085-1-git-send-email-mgorman@techsingularity.net> Johannes reported that the comment about buffer_heads_over_limit in balance_pgdat only made sense in the context of the patch. This patch clarifies the reasoning and how it applies to 32 and 64 bit systems. This is a fix to the mmotm patch mm-vmscan-have-kswapd-reclaim-from-all-zones-if-reclaiming-and-buffer_heads_over_limit.patch Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- mm/vmscan.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index d079210d46ee..21eae17ee730 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3131,12 +3131,13 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) /* * If the number of buffer_heads exceeds the maximum allowed - * then consider reclaiming from all zones. This is not - * specific to highmem which may not exist but it is it is - * expected that buffer_heads are stripped in writeback. - * Reclaim may still not go ahead if all eligible zones - * for the original allocation request are balanced to - * avoid excessive reclaim from kswapd. + * then consider reclaiming from all zones. This has a dual + * purpose -- on 64-bit systems it is expected that + * buffer_heads are stripped during active rotation. On 32-bit + * systems, highmem pages can pin lowmem memory and shrinking + * buffers can relieve lowmem pressure. Reclaim may still not + * go ahead if all eligible zones for the original allocation + * request are balanced to avoid excessive reclaim from kswapd. */ if (buffer_heads_over_limit) { for (i = MAX_NR_ZONES - 1; i >= 0; i--) { -- 2.6.4
WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@techsingularity.net> To: Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, Minchan Kim <minchan@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@techsingularity.net> Subject: [PATCH 1/4] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit -fix Date: Wed, 13 Jul 2016 11:00:01 +0100 [thread overview] Message-ID: <1468404004-5085-2-git-send-email-mgorman@techsingularity.net> (raw) In-Reply-To: <1468404004-5085-1-git-send-email-mgorman@techsingularity.net> Johannes reported that the comment about buffer_heads_over_limit in balance_pgdat only made sense in the context of the patch. This patch clarifies the reasoning and how it applies to 32 and 64 bit systems. This is a fix to the mmotm patch mm-vmscan-have-kswapd-reclaim-from-all-zones-if-reclaiming-and-buffer_heads_over_limit.patch Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- mm/vmscan.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index d079210d46ee..21eae17ee730 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3131,12 +3131,13 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) /* * If the number of buffer_heads exceeds the maximum allowed - * then consider reclaiming from all zones. This is not - * specific to highmem which may not exist but it is it is - * expected that buffer_heads are stripped in writeback. - * Reclaim may still not go ahead if all eligible zones - * for the original allocation request are balanced to - * avoid excessive reclaim from kswapd. + * then consider reclaiming from all zones. This has a dual + * purpose -- on 64-bit systems it is expected that + * buffer_heads are stripped during active rotation. On 32-bit + * systems, highmem pages can pin lowmem memory and shrinking + * buffers can relieve lowmem pressure. Reclaim may still not + * go ahead if all eligible zones for the original allocation + * request are balanced to avoid excessive reclaim from kswapd. */ if (buffer_heads_over_limit) { for (i = MAX_NR_ZONES - 1; i >= 0; i--) { -- 2.6.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-07-13 10:00 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-13 10:00 [PATCH 0/4] Follow-up fixes to node-lru series v1 Mel Gorman 2016-07-13 10:00 ` Mel Gorman 2016-07-13 10:00 ` Mel Gorman [this message] 2016-07-13 10:00 ` [PATCH 1/4] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit -fix Mel Gorman 2016-07-13 13:10 ` Johannes Weiner 2016-07-13 13:10 ` Johannes Weiner 2016-07-14 1:22 ` Minchan Kim 2016-07-14 1:22 ` Minchan Kim 2016-07-13 10:00 ` [PATCH 2/4] mm: vmstat: account per-zone stalls and pages skipped during reclaim -fix Mel Gorman 2016-07-13 10:00 ` Mel Gorman 2016-07-13 13:10 ` Johannes Weiner 2016-07-13 13:10 ` Johannes Weiner 2016-07-14 14:45 ` Vlastimil Babka 2016-07-14 14:45 ` Vlastimil Babka 2016-07-13 10:00 ` [PATCH 3/4] mm, page_alloc: fix dirtyable highmem calculation Mel Gorman 2016-07-13 10:00 ` Mel Gorman 2016-07-13 13:15 ` Johannes Weiner 2016-07-13 13:15 ` Johannes Weiner 2016-07-14 15:22 ` Vlastimil Babka 2016-07-14 15:22 ` Vlastimil Babka 2016-07-13 10:00 ` [PATCH 4/4] mm: move most file-based accounting to the node -fix Mel Gorman 2016-07-13 10:00 ` Mel Gorman 2016-07-13 13:16 ` Johannes Weiner 2016-07-13 13:16 ` Johannes Weiner
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