From: Ric Wheeler <rwheeler@redhat.com>
Subject: Re: transaction batching performance & multi-threaded synchronous
 writers
Date: Tue, 15 Jul 2008 18:33:23 -0400
Message-ID: <487D25B3.3030209@redhat.com>
References: <487B7B9B.3020001@gmail.com> <20080715183904.GC30311@unused.rdu.redhat.com> <20080715201010.GD30311@unused.rdu.redhat.com> <20080715204356.GE30311@unused.rdu.redhat.com>
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Cc: linux-ext4@vger.kernel.org, adilger@sun.com
To: Josef Bacik <jbacik@redhat.com>
In-Reply-To: <20080715204356.GE30311@unused.rdu.redhat.com>
Sender: linux-ext4-owner@vger.kernel.org

Josef Bacik wrote:
> On Tue, Jul 15, 2008 at 04:10:10PM -0400, Josef Bacik wrote:
>   
>> On Tue, Jul 15, 2008 at 02:39:04PM -0400, Josef Bacik wrote:
>>     
>>> On Mon, Jul 14, 2008 at 12:15:23PM -0400, Ric Wheeler wrote:
>>>       
>>>> Here is a pointer to the older patch & some results:
>>>>
>>>> http://www.spinics.net/lists/linux-fsdevel/msg13121.html
>>>>
>>>> I will retry this on some updated kernels, but would not expect to see a 
>>>> difference since the code has not been changed ;-)
>>>>
>>>>         
>>> Ok here are the numbers with the original idea I had proposed.
>>>
>>> type	threads		base	patch	speedup
>>> sata	1		17.9	17.3	0.97
>>> sata	2		33.2	34.2	1.03
>>> sata	4		58.4	63.6	1.09
>>> sata	8		78.8	80.8	1.03
>>> sata	16		94.4	97.6	1.16
>>>
>>> ram	1		2394.4	1878.0	0.78
>>> ram	2		989.6	2041.1	2.06
>>> ram	4		1466.1	3201.8	2.18
>>> ram	8		1858.1	3362.8	1.81
>>> ram	16		3008.0	3227.7	1.07
>>>
>>> I've got to find a fast disk array to test this with, but the ramdisk results
>>> make me happy, though they were kind of irratic, so I think the fast disk array
>>> will be a more stable measure of how well this patch does, but it definitely
>>> doesn't hurt the slow case, and brings stability to the fast case.  Thanks much,
>>>
>>>       
>> Hmm talking with ric I should just leave the single thread stuff alone.  That
>> removes the slight speed regression seen above.  Thanks,
>>
>>     
>
> Here are the results with the single thread stuff put back in and with 250HZ
> instead of 1000HZ from before
>
> type	threads		base	patch
> sata	1		21.8	21.6
> sata	2		26.2	34.6
> sata	4		48.0	58.0
> sata	8		70.4	75.2
> sata	16		89.6	101.1
>
> ram	1		2505.4	2422.0
> ram	2		463.8	3462.3
> ram	4		330.4	3653.9
> ram	8		995.1	3592.4
> ram	16		1335.2	3806.5
>
> Thanks,
>
> Josef 
>   
These numbers are pretty impressive - we need to get a run on an array 
backed file system as well to round out the picture and possibly an SSD 
(anyone have one out there to play with)?

ric