what sort of controller do you have and how is it connected ?
are you testing on a filesystem or directly at the md device ?

2013/12/16 lilofile [off-list ref]:

Yes,I test like what  you say,but the result is the same.


------------------------------------------------------------------
发件人：Tommy Apel [off-list ref]
发送时间：2013年12月16日(星期一) 20:45
收件人：lilofile [off-list ref]
抄　送：linux-raid Raid [off-list ref]
主　题：Re: 答复：答复：two raid5 performance

try this, this will put a dd on different cores so that you don't
starve one core with both dd processes
taskset 1 dd if=/dev/zero of=raidset1
taskset 2 dd if=/dev/zero of=raidset2

2013/12/16 lilofile [off-list ref]:

quoted

In dd test,I use Linux top tools,and I found 2 raid use different cores, CPU  occupancy of each raid5 reach to 80% , is any lock contention  between two raid?


------------------------------------------------------------------
发件人：Tommy Apel [off-list ref]
发送时间：2013年12月16日(星期一) 16:13
收件人：lilofile [off-list ref]
抄　送：Pieter De Wit [off-list ref]; linux-raid Raid [off-list ref]; Tommy Apel [off-list ref]
主　题：Re: 答复：two raid5 performance

Try to use taskset command to make sure the dd commands are handled by different cores otherwise you'll starve 1 core.
On Dec 16, 2013 8:58 AM, "lilofile" [off-list ref] wrote:

the disks involved in the array is sTEC ssd disk,they are connected by mpt2sas 6Gb/s





------------------------------------------------------------------

发件人：Pieter De Wit [off-list ref]

发送时间：2013年12月16日(星期一) 15:52

收件人：lilofile [off-list ref]; unlisted-recipients: <unlisted-recipients:>

抄　送：linux-raid [off-list ref]

主　题：Re: two raid5 performance



On 16/12/2013 14:07, lilofile wrote:

quoted

when I Create a raid5,dd  1M block size,the performance can reached to 1GB/s

quoted

when I create another raid5,dd 1M block size ,the performance can reached to 1GB/s

quoted

when I simultaneously dd the two different raid,the total performance only reached to 1.4GB/s,why can not reached to 2GB/s.

quoted

quoted

the memory is 32GB,CPU is x5660,the stripe size is 4096

quoted

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What is the disks involved in the array ? How are they connected ?

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