From: Johannes Weiner <jweiner@redhat.com>
To: Shawn Bohrer <sbohrer@rgmadvisors.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fadvise: only initiate writeback for specified range with FADV_DONTNEED
Date: Tue, 1 Nov 2011 16:05:55 +0100 [thread overview]
Message-ID: <20111101150555.GC19965@redhat.com> (raw)
In-Reply-To: <1320077819-1494-1-git-send-email-sbohrer@rgmadvisors.com>
On Mon, Oct 31, 2011 at 11:16:59AM -0500, Shawn Bohrer wrote:
> Previously POSIX_FADV_DONTNEED would start writeback for the entire file
> when the bdi was not write congested. This negatively impacts
> performance if the file contians dirty pages outside of the requested
> range. This change uses __filemap_fdatawrite_range() to only initiate
> writeback for the requested range.
>
> Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
It probably makes sense for some cases to take advantage of the disk
head being nearby and flush more than requested.
But I can certainly see this go wrong by taking away the write-caching
benefits for the rest of the file just because a small part of it was
fadvised.
Acked-by: Johannes Weiner <jweiner@redhat.com>
WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <jweiner@redhat.com>
To: Shawn Bohrer <sbohrer@rgmadvisors.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fadvise: only initiate writeback for specified range with FADV_DONTNEED
Date: Tue, 1 Nov 2011 16:05:55 +0100 [thread overview]
Message-ID: <20111101150555.GC19965@redhat.com> (raw)
In-Reply-To: <1320077819-1494-1-git-send-email-sbohrer@rgmadvisors.com>
On Mon, Oct 31, 2011 at 11:16:59AM -0500, Shawn Bohrer wrote:
> Previously POSIX_FADV_DONTNEED would start writeback for the entire file
> when the bdi was not write congested. This negatively impacts
> performance if the file contians dirty pages outside of the requested
> range. This change uses __filemap_fdatawrite_range() to only initiate
> writeback for the requested range.
>
> Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com>
It probably makes sense for some cases to take advantage of the disk
head being nearby and flush more than requested.
But I can certainly see this go wrong by taking away the write-caching
benefits for the rest of the file just because a small part of it was
fadvised.
Acked-by: Johannes Weiner <jweiner@redhat.com>
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next prev parent reply other threads:[~2011-11-01 15:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-31 16:16 [PATCH] fadvise: only initiate writeback for specified range with FADV_DONTNEED Shawn Bohrer
2011-10-31 16:16 ` Shawn Bohrer
2011-11-01 15:05 ` Johannes Weiner [this message]
2011-11-01 15:05 ` Johannes Weiner
2011-11-22 23:01 ` [PATCH resend] " Shawn Bohrer
2011-11-22 23:01 ` Shawn Bohrer
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