linux-kernel - Re: [PATCH 14/14] mm: Account for WRITEBACK_TEMP in balance_dirty

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Message-ID: <20121121115314.20471.52148.stgit@maximpc.sw.ru>
Date:	Wed, 21 Nov 2012 16:01:28 +0400
From:	Maxim Patlasov <mpatlasov@...allels.com>
To:	miklos@...redi.hu
Cc:	dev@...allels.com, xemul@...allels.com,
	fuse-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	jbottomley@...allels.com, linux-mm@...ck.org,
	viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 14/14] mm: Account for WRITEBACK_TEMP in
 balance_dirty_pages

Added linux-mm@ to cc:. The patch can stand on it's own.

> Make balance_dirty_pages start the throttling when the WRITEBACK_TEMP
> counter is high enough. This prevents us from having too many dirty
> pages on fuse, thus giving the userspace part of it a chance to write
> stuff properly.
> 
> Note, that the existing balance logic is per-bdi, i.e. if the fuse
> user task gets stuck in the function this means, that it either
> writes to the mountpoint it serves (but it can deadlock even without
> the writeback) or it is writing to some _other_ dirty bdi and in the
> latter case someone else will free the memory for it.

Signed-off-by: Maxim V. Patlasov <MPatlasov@...allels.com>
Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>
---
 mm/page-writeback.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 830893b..499a606 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1220,7 +1220,8 @@ static void balance_dirty_pages(struct address_space *mapping,
 		 */
 		nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
 					global_page_state(NR_UNSTABLE_NFS);
-		nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK);
+		nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK) +
+			global_page_state(NR_WRITEBACK_TEMP);
 
 		global_dirty_limits(&background_thresh, &dirty_thresh);
 

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