From: Nick Piggin <npiggin@suse.de>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org,
torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
xfs@oss.sgi.com
Subject: Re: [PATCH 6/6] writeback: limit write_cache_pages integrity scanning to current EOF
Date: Tue, 8 Jun 2010 15:38:31 +1000 [thread overview]
Message-ID: <20100608053831.GR26335@laptop> (raw)
In-Reply-To: <1275957487-23633-7-git-send-email-david@fromorbit.com>
On Tue, Jun 08, 2010 at 10:38:07AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> sync can currently take a really long time if a concurrent writer is
> extending a file. The problem is that the dirty pages on the address
> space grow in the same direction as write_cache_pages scans, so if
> the writer keeps ahead of writeback, the writeback will not
> terminate until the writer stops adding dirty pages.
>
> For a data integrity sync, we only need to write the pages dirty at
> the time we start the writeback, so we can stop scanning once we get
> to the page that was at the end of the file at the time the scan
> started.
>
> This will prevent operations like copying a large file preventing
> sync from completing as it will not write back pages that were
> dirtied after the sync was started. This does not impact the
> existing integrity guarantees, as any dirty page (old or new)
> within the EOF range at the start of the scan will still be
> captured.
>
> This patch will not prevent sync from blocking on large writes into
> holes.
The writes don't have to be into holes to cause this starvation
problem, do they?
> That requires more complex intervention while this patch only
> addresses the common append-case of this sync holdoff.
Jan's tagging patch looks pretty good to me and isn't so complex.
I think we should just take that.
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WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <npiggin@suse.de>
To: Dave Chinner <david@fromorbit.com>
Cc: torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, xfs@oss.sgi.com,
akpm@linux-foundation.org
Subject: Re: [PATCH 6/6] writeback: limit write_cache_pages integrity scanning to current EOF
Date: Tue, 8 Jun 2010 15:38:31 +1000 [thread overview]
Message-ID: <20100608053831.GR26335@laptop> (raw)
In-Reply-To: <1275957487-23633-7-git-send-email-david@fromorbit.com>
On Tue, Jun 08, 2010 at 10:38:07AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> sync can currently take a really long time if a concurrent writer is
> extending a file. The problem is that the dirty pages on the address
> space grow in the same direction as write_cache_pages scans, so if
> the writer keeps ahead of writeback, the writeback will not
> terminate until the writer stops adding dirty pages.
>
> For a data integrity sync, we only need to write the pages dirty at
> the time we start the writeback, so we can stop scanning once we get
> to the page that was at the end of the file at the time the scan
> started.
>
> This will prevent operations like copying a large file preventing
> sync from completing as it will not write back pages that were
> dirtied after the sync was started. This does not impact the
> existing integrity guarantees, as any dirty page (old or new)
> within the EOF range at the start of the scan will still be
> captured.
>
> This patch will not prevent sync from blocking on large writes into
> holes.
The writes don't have to be into holes to cause this starvation
problem, do they?
> That requires more complex intervention while this patch only
> addresses the common append-case of this sync holdoff.
Jan's tagging patch looks pretty good to me and isn't so complex.
I think we should just take that.
next prev parent reply other threads:[~2010-06-08 5:36 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-08 0:38 [PATCH 0/6] writeback: tracing and fixes V4 Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 0:38 ` [PATCH 1/6] writeback: initial tracing support Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 0:38 ` [PATCH 2/6] writeback: Add tracing to balance_dirty_pages Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 0:38 ` [PATCH 3/6] writeback: Add tracing to write_cache_pages Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 0:38 ` [PATCH 4/6] writeback: pay attention to wbc->nr_to_write in write_cache_pages Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 5:43 ` Nick Piggin
2010-06-08 5:43 ` Nick Piggin
2010-06-08 0:38 ` [PATCH 5/6] xfs: remove nr_to_write writeback windup Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 0:38 ` [PATCH 6/6] writeback: limit write_cache_pages integrity scanning to current EOF Dave Chinner
2010-06-08 0:38 ` Dave Chinner
2010-06-08 5:38 ` Nick Piggin [this message]
2010-06-08 5:38 ` Nick Piggin
2010-06-08 6:59 ` Dave Chinner
2010-06-08 6:59 ` Dave Chinner
2010-06-08 5:44 ` [PATCH 0/6] writeback: tracing and fixes V4 Nick Piggin
2010-06-08 5:44 ` Nick Piggin
2010-06-08 17:41 ` Linus Torvalds
2010-06-08 17:41 ` Linus Torvalds
2010-06-08 17:50 ` Andrew Morton
2010-06-08 17:50 ` Andrew Morton
2010-06-08 22:46 ` Dave Chinner
2010-06-08 22:46 ` Dave Chinner
-- strict thread matches above, loose matches on Subject: below --
2010-06-03 23:55 [PATCH 0/6] writeback: tracing and fixes V3 Dave Chinner
2010-06-03 23:55 ` [PATCH 6/6] writeback: limit write_cache_pages integrity scanning to current EOF Dave Chinner
2010-06-03 23:55 ` Dave Chinner
2010-06-04 7:52 ` Christoph Hellwig
2010-06-04 7:52 ` Christoph Hellwig
2010-06-04 7:56 ` Nick Piggin
2010-06-04 7:56 ` Nick Piggin
2010-05-25 10:54 [PATCH 0/6] writeback: tracing and fixes Dave Chinner
2010-05-25 10:54 ` [PATCH 6/6] writeback: limit write_cache_pages integrity scanning to current EOF Dave Chinner
2010-05-25 10:54 ` Dave Chinner
2010-05-27 21:33 ` Andrew Morton
2010-05-27 21:33 ` Andrew Morton
2010-05-28 1:23 ` Dave Chinner
2010-05-28 1:23 ` Dave Chinner
2010-05-28 5:06 ` Nick Piggin
2010-05-28 5:06 ` Nick Piggin
2010-06-01 15:54 ` Jan Kara
2010-06-01 15:54 ` Jan Kara
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