linux-kernel - [PATCH 16/16] mm: Account for the number of times direct reclaimers get throttled

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1342075232-29267-17-git-send-email-mgorman@suse.de>
Date:	Thu, 12 Jul 2012 07:40:32 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linux-MM <linux-mm@...ck.org>,
	Linux-Netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>, Neil Brown <neilb@...e.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mike Christie <michaelc@...wisc.edu>,
	Eric B Munson <emunson@...bm.net>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Sebastian Andrzej Siewior <sebastian@...akpoint.cc>,
	Mel Gorman <mgorman@...e.de>
Subject: [PATCH 16/16] mm: Account for the number of times direct reclaimers get throttled

Under significant pressure when writing back to network-backed storage,
direct reclaimers may get throttled. This is expected to be a
short-lived event and the processes get woken up again but processes do
get stalled. This patch counts how many times such stalling occurs. It's
up to the administrator whether to reduce these stalls by increasing
min_free_kbytes.

Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 include/linux/vm_event_item.h |    1 +
 mm/vmscan.c                   |    3 +++
 mm/vmstat.c                   |    1 +
 3 files changed, 5 insertions(+)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 06f8e38..57f7b10 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -30,6 +30,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		FOR_ALL_ZONES(PGSTEAL_DIRECT),
 		FOR_ALL_ZONES(PGSCAN_KSWAPD),
 		FOR_ALL_ZONES(PGSCAN_DIRECT),
+		PGSCAN_DIRECT_THROTTLE,
 #ifdef CONFIG_NUMA
 		PGSCAN_ZONE_RECLAIM_FAILED,
 #endif
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ffe58d3..a75b083 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2177,6 +2177,9 @@ static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
 	if (pfmemalloc_watermark_ok(pgdat))
 		return;
 
+	/* Account for the throttling */
+	count_vm_event(PGSCAN_DIRECT_THROTTLE);
+
 	/*
 	 * If the caller cannot enter the filesystem, it's possible that it
 	 * is due to the caller holding an FS lock or performing a journal
diff --git a/mm/vmstat.c b/mm/vmstat.c
index e4db312..dcc3858 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -744,6 +744,7 @@ const char * const vmstat_text[] = {
 	TEXTS_FOR_ZONES("pgsteal_direct")
 	TEXTS_FOR_ZONES("pgscan_kswapd")
 	TEXTS_FOR_ZONES("pgscan_direct")
+	"pgscan_direct_throttle",
 
 #ifdef CONFIG_NUMA
 	"zone_reclaim_failed",
-- 
1.7.9.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/