raid acceleration and asynchronous offload api for 2.6.22
Quoted 3 lines · Ronen Shitrit
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.
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 10 lines · Tomasz Chmielewski
Quoted 3 lines · Ronen Shitrit
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:
Quoted 8 lines
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/secBut are 10 times worse (Timing buffered disk reads) when we access partitions:
There seems to be another side effect when comparing DMA engine in 2.6.17-iop1 to 2.6.21-iop1: network performance.
For simple network tests, I use "netperf" tool to measure network performance.
With 2.6.17-iop1 and all DMA offloading options enabled (selectable in System type ---> IOP3xx Implementation Options --->), I get nearly 25 MB/s throughput.
With 2.6.21-iop1 and all DMA offloading optons enabled (moved to Device Drivers ---> DMA Engine support --->), I get only about 10 MB/s throughput. Additionally, on 2.6.21-iop1, I get lots of "dma_cookie < 0" printed by the kernel.
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org