From: Christoph Hellwig <hch@infradead.org>
To: Chris Mason <chris.mason@oracle.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Jeff Moyer <jmoyer@redhat.com>
Subject: Re: aio: bump i_count instead of using igrab
Date: Mon, 23 Aug 2010 10:50:31 -0400 [thread overview]
Message-ID: <20100823145031.GA1279@infradead.org> (raw)
In-Reply-To: <20100823144755.GP21975@think>
On Mon, Aug 23, 2010 at 10:47:55AM -0400, Chris Mason wrote:
> The aio batching code is using igrab to get an extra reference on the
> inode so it can safely batch. igrab will go ahead and take the global
> inode spinlock, which can be a bottleneck on large machines doing lots
> of AIO.
>
> In this case, igrab isn't required because we already have a reference
> on the file handle. It is safe to just bump the i_count directly
> on the inode.
>
> Benchmarking shows this patch brings IOP/s on tons of flash up by about
> 2.5X.
There's some places in XFS where we do the same, and it showed up as a
bottle neck before. Instead of open coding the increment we have
a wrapper that includes and assert that the numbers is always positive.
I think we really want a proper helper for general use instead of
completly opencoding it.
next prev parent reply other threads:[~2010-08-23 14:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-23 14:47 aio: bump i_count instead of using igrab Chris Mason
2010-08-23 14:50 ` Christoph Hellwig [this message]
2010-08-23 15:00 ` Chris Mason
2010-08-23 17:26 ` Jeff Moyer
2010-08-24 7:33 ` Nick Piggin
2010-08-23 21:18 ` Jeff Moyer
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