Ronen Shitrit wrote:
The resync numbers you sent, looks very promising :)
Do you have any performance numbers that you can share for these set of
patches, which shows the Rd/Wr IO bandwidth.
I have some simple tests made with hdparm, with the results I don't
understand.
We see hdparm results are fine if we access the whole device:
thecus:~# hdparm -Tt /dev/sdd
/dev/sdd:
Timing cached reads: 392 MB in 2.00 seconds = 195.71 MB/sec
Timing buffered disk reads: 146 MB in 3.01 seconds = 48.47 MB/sec
But are 10 times worse (Timing buffered disk reads) when we access
partitions:
thecus:/# hdparm -Tt /dev/sdc1 /dev/sdd1
/dev/sdc1:
Timing cached reads: 396 MB in 2.01 seconds = 197.18 MB/sec
Timing buffered disk reads: 16 MB in 3.32 seconds = 4.83 MB/sec
/dev/sdd1:
Timing cached reads: 394 MB in 2.00 seconds = 196.89 MB/sec
Timing buffered disk reads: 16 MB in 3.13 seconds = 5.11 MB/sec
Why is it so much worse?
I used 2.6.21-iop1 patches from http://sf.net/projects/xscaleiop; right
now I use 2.6.17-iop1, for which the results are ~35 MB/s when accessing
a device (/dev/sdd) or a partition (/dev/sdd1).
In kernel config, I enabled Intel DMA engines.
The device I use is Thecus n4100, it is "Platform: IQ31244 (XScale)",
and has 600 MHz CPU.
--
Tomasz Chmielewski
http://wpkg.org
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