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From: Olaf Weber <olaf@sgi.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-mm@kvack.org, "MASON, CHRISTOPHER" <CHRIS.MASON@oracle.com>,
	xfs mailing list <xfs@oss.sgi.com>
Subject: Re: [PATCH] bump up nr_to_write in xfs_vm_writepage
Date: Tue, 07 Jul 2009 11:07:30 +0200	[thread overview]
Message-ID: <bzyd48cc14d.fsf@fransum.emea.sgi.com> (raw)
In-Reply-To: <4A4D26C5.9070606@redhat.com> (Eric Sandeen's message of "Thu, 02 Jul 2009 16:29:41 -0500")

Eric Sandeen writes:

> Talking w/ someone who had a raid6 of 15 drives on an areca
> controller, he wondered why he could only get 300MB/s or so
> out of a streaming buffered write to xfs like so:

> dd if=/dev/zero of=/mnt/storage/10gbfile bs=128k count=81920
> 10737418240 bytes (11 GB) copied, 34.294 s, 313 MB/s

> when the same write directly to the device was going closer
> to 700MB/s...

> With the following change things get moving again for xfs:

> dd if=/dev/zero of=/mnt/storage/10gbfile bs=128k count=81920
> 10737418240 bytes (11 GB) copied, 16.2938 s, 659 MB/s

> Chris had sent out something similar at Christoph's suggestion,
> and Christoph reminded me of it, and I tested it a variant of
> it, and it seems to help shockingly well.

> Feels like a bandaid though; thoughts?  Other tests to do?

If the nr_to_write calculation really yields a value that is too
small, shouldn't it be fixed elsewhere?

Otherwise it might make sense to make the fudge factor tunable.

> +
> +	/*
> +	 *  VM calculation for nr_to_write seems off.  Bump it way
> +	 *  up, this gets simple streaming writes zippy again.
> +	 */
> +	wbc->nr_to_write *= 4;
> +

-- 
Olaf Weber                 SGI               Phone:  +31(0)30-6696752
                           Veldzigt 2b       Fax:    +31(0)30-6696799
Technical Lead             3454 PW de Meern  Vnet:   955-7151
Storage Software           The Netherlands   Email:  olaf@sgi.com

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WARNING: multiple messages have this Message-ID (diff)
From: Olaf Weber <olaf@sgi.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: xfs mailing list <xfs@oss.sgi.com>,
	Christoph Hellwig <hch@infradead.org>,
	linux-mm@kvack.org, "MASON, CHRISTOPHER" <CHRIS.MASON@oracle.com>
Subject: Re: [PATCH] bump up nr_to_write in xfs_vm_writepage
Date: Tue, 07 Jul 2009 11:07:30 +0200	[thread overview]
Message-ID: <bzyd48cc14d.fsf@fransum.emea.sgi.com> (raw)
In-Reply-To: <4A4D26C5.9070606@redhat.com> (Eric Sandeen's message of "Thu, 02 Jul 2009 16:29:41 -0500")

Eric Sandeen writes:

> Talking w/ someone who had a raid6 of 15 drives on an areca
> controller, he wondered why he could only get 300MB/s or so
> out of a streaming buffered write to xfs like so:

> dd if=/dev/zero of=/mnt/storage/10gbfile bs=128k count=81920
> 10737418240 bytes (11 GB) copied, 34.294 s, 313 MB/s

> when the same write directly to the device was going closer
> to 700MB/s...

> With the following change things get moving again for xfs:

> dd if=/dev/zero of=/mnt/storage/10gbfile bs=128k count=81920
> 10737418240 bytes (11 GB) copied, 16.2938 s, 659 MB/s

> Chris had sent out something similar at Christoph's suggestion,
> and Christoph reminded me of it, and I tested it a variant of
> it, and it seems to help shockingly well.

> Feels like a bandaid though; thoughts?  Other tests to do?

If the nr_to_write calculation really yields a value that is too
small, shouldn't it be fixed elsewhere?

Otherwise it might make sense to make the fudge factor tunable.

> +
> +	/*
> +	 *  VM calculation for nr_to_write seems off.  Bump it way
> +	 *  up, this gets simple streaming writes zippy again.
> +	 */
> +	wbc->nr_to_write *= 4;
> +

-- 
Olaf Weber                 SGI               Phone:  +31(0)30-6696752
                           Veldzigt 2b       Fax:    +31(0)30-6696799
Technical Lead             3454 PW de Meern  Vnet:   955-7151
Storage Software           The Netherlands   Email:  olaf@sgi.com

--
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  parent reply	other threads:[~2009-07-07  9:07 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-02 21:29 [PATCH] bump up nr_to_write in xfs_vm_writepage Eric Sandeen
2009-07-02 21:29 ` Eric Sandeen
2009-07-03 23:51 ` Michael Monnerie
2009-07-07  9:07 ` Olaf Weber [this message]
2009-07-07  9:07   ` Olaf Weber
2009-07-07 10:19   ` Christoph Hellwig
2009-07-07 10:19     ` Christoph Hellwig
2009-07-07 10:33     ` KOSAKI Motohiro
2009-07-07 10:33       ` KOSAKI Motohiro
2009-07-07 10:44       ` Christoph Hellwig
2009-07-07 10:44         ` Christoph Hellwig
2009-07-09  2:04         ` KOSAKI Motohiro
2009-07-09  2:04           ` KOSAKI Motohiro
2009-07-09 13:01           ` Chris Mason
2009-07-09 13:01             ` Chris Mason
2009-07-10  7:12             ` KOSAKI Motohiro
2009-07-10  7:12               ` KOSAKI Motohiro
2009-07-24  5:20               ` Felix Blyakher
2009-07-24  5:20                 ` Felix Blyakher
2009-07-24  5:33                 ` KOSAKI Motohiro
2009-07-24  5:33                   ` KOSAKI Motohiro
2009-07-24 12:05                 ` Chris Mason
2009-07-24 12:05                   ` Chris Mason
2009-07-07 11:37     ` Olaf Weber
2009-07-07 11:37       ` Olaf Weber
2009-07-07 14:46       ` Christoph Hellwig
2009-07-07 14:46         ` Christoph Hellwig
2009-07-07 15:17 ` Chris Mason
2009-07-07 15:17   ` Chris Mason

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