With a fresh install of the O/S on a non-broken motherboard, the change to
/proc/sys/vm/dirty_ratio
restores most of the lost performance from 2.6.18,
as of 2.6.20-rc4. The difference is 10% to 15% without the dirty_ratio
change (40 is the default, 10 gives the old performance).
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 33571 MS, Rate: 244.020, to
/s0/GigaData.0
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 33480 MS, Rate: 244.683, to
/s2/GigaData.0
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 33570 MS, Rate: 244.027, to
/s1/GigaData.0
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 33579 MS, Rate: 243.962, to
/s3/GigaData.0
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 31486 MS, Rate: 260.179, to
/s0/GigaData.1
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 31537 MS, Rate: 259.758, to
/s2/GigaData.1
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 31538 MS, Rate: 259.750, to
/s3/GigaData.1
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 31549 MS, Rate: 259.660, to
/s1/GigaData.1
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 32205 MS, Rate: 254.370, to
/s2/GigaData.2
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 32205 MS, Rate: 254.370, to
/s1/GigaData.2
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 32218 MS, Rate: 254.268, to
/s3/GigaData.2
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 32220 MS, Rate: 254.252, to
/s0/GigaData.2
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 33536 MS, Rate: 244.275, to
/s0/GigaData.3
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 33583 MS, Rate: 243.933, to
/s3/GigaData.3
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 34016 MS, Rate: 240.828, to
/s1/GigaData.3
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 34018 MS, Rate: 240.814, to
/s2/GigaData.3
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 34121 MS, Rate: 240.087, to
/s1/GigaData.4
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 34123 MS, Rate: 240.073, to
/s0/GigaData.4
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 34114 MS, Rate: 240.136, to
/s2/GigaData.4
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 34122 MS, Rate: 240.080, to
/s3/GigaData.4
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30386 MS, Rate: 269.598, to
/s0/GigaData.9
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30384 MS, Rate: 269.616, to
/s1/GigaData.9
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30717 MS, Rate: 266.693, to
/s3/GigaData.9
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30726 MS, Rate: 266.615, to
/s2/GigaData.9
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30088 MS, Rate: 272.268, to
/s0/GigaData.10
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30079 MS, Rate: 272.349, to
/s2/GigaData.10
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 30086 MS, Rate: 272.286, to
/s1/GigaData.10
Data: Writing, 8192 MB, Buffer: 128 KB, Time: 29989 MS, Rate: 273.167, to
/s3/GigaData.10
So whatever needs to be tweaked in the VM system seems to be the key.
Thanks to all for getting this regression repaired.
Berkley
David Chinner wrote:
> On Tue, Jan 09, 2007 at 12:22:12PM +1100, David Chinner wrote:
>
>> On Mon, Jan 08, 2007 at 11:13:43AM -0600, Mr. Berkley Shands wrote:
>>
>>> My testbench is a 4 core Opteron (dual 275's) into
>>> two LSI8408E SAS controllers, into 16 Seagate 7200.10 320GB satas.
>>> Redhat ES4.4 (Centos 4.4). A slightly newer parted is needed
>>> than the contemporary of Moses that is shipped with the O/S.
>>>
>>> I have a standard burn in script that takes the 4 4-drive raid0's
>>> and puts a GPT label on them, aligns the partitions to stripe
>>> boundary's. It then proceeds to write 8GB files concurrently
>>> onto all 4 raid drives.
>>>
>
> I just ran up a similar test - single large file per device on a 4
> core Xeon (woodcrest) with 16GB RAM, a single PCI-X SAS HBA and
> 12x10krpm 300GB SAS disks split into 3x4 disk dm raid zero stripes
> on 2.6.18 and 2.6.20-rc3.
>
> I see the same thing - 2.6.20-rc3 is more erractic and quite a
> bit slower than 2.6.18 when going through XFS.
>
> I suggest trying this on 2.6.20-rc3:
>
> # echo 10 > /proc/sys/vm/dirty_ratio
>
> That restored most of the lost performance and consistency
> in my testing....
>
> Cheers,
>
> Dave.
>
--
//E. F. Berkley Shands, MSc//
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