I have a question, when I use multiple writer threads (2 or 3) I see
550-600 MiB/s write speed (vmstat) but when using only 1 thread, ~420-430
MiB/s... Also without tweaking, SW RAID is very slow (180-200 MiB/s) using
the same disks.
Justin.
On Wed, 26 Sep 2007, Bryan J Smith wrote:
Everyone can play local benchmarking games all they want,
and software RAID will almost always be faster, significantly at times.
What matters is actual, multiple client performance under full load.
Anything less is a completely irrelevant.
--
Bryan J Smith - mailto:b.j.smith@xxxxxxxx
http://thebs413.blogspot.com
Sent via BlackBerry from T-Mobile
-----Original Message-----
From: Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>
Date: Wed, 26 Sep 2007 05:52:39
To:Ralf Gross <Ralf-Lists@xxxxxxxxxxxx>
Cc:linux-xfs@xxxxxxxxxxx, linux-raid@xxxxxxxxxxxxxxx
Subject: Re: mkfs options for a 16x hw raid5 and xfs (mostly large files)
On Wed, 26 Sep 2007, Ralf Gross wrote:
Justin Piszcz schrieb:
What was the command line you used for that output?
tiobench.. ?
tiobench --numruns 3 --threads 1 --threads 2 --block 4096 --size 20000
--size 20000 because the server has 16 GB RAM.
Ralf
Here is my output on my SW RAID5 keep in mind it is currently being used so the numbers are a little slower than they probably should be:
My machine only has 8 GiB of memory but I used the same command you did:
This is with the 2.6.22.6 kernel, the 2.6.23-rcX/final when released is supposed to have the SW RAID5 accelerator code, correct?
Unit information
================
File size = megabytes
Blk Size = bytes
Rate = megabytes per second
CPU% = percentage of CPU used during the test
Latency = milliseconds
Lat% = percent of requests that took longer than X seconds
CPU Eff = Rate divided by CPU% - throughput per cpu load
Sequential Reads
File Blk Num Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
2.6.22.6 20000 4096 1 523.01 45.79% 0.022 510.77 0.00000 0.00000 1142
2.6.22.6 20000 4096 2 501.29 85.84% 0.046 855.59 0.00000 0.00000 584
Random Reads
File Blk Num Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
2.6.22.6 20000 4096 1 0.90 0.276% 13.003 74.41 0.00000 0.00000 326
2.6.22.6 20000 4096 2 1.61 1.167% 14.443 126.43 0.00000 0.00000 137
Sequential Writes
File Blk Num Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
2.6.22.6 20000 4096 1 363.46 75.72% 0.030 2757.45 0.00000 0.00000 480
2.6.22.6 20000 4096 2 394.45 287.9% 0.056 2798.92 0.00000 0.00000 137
Random Writes
File Blk Num Avg Maximum Lat% Lat% CPU
Identifier Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
---------------------------- ------ ----- --- ------ ------ --------- ----------- -------- -------- -----
2.6.22.6 20000 4096 1 3.16 1.752% 0.011 1.02 0.00000 0.00000 180
2.6.22.6 20000 4096 2 3.07 3.769% 0.013 0.10 0.00000 0.00000 82
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