i wrote another program to read from device and then discard.
./synctest /dev/md1
Personalities : [linear] [raid0] [raid1] [raid5] [multipath]
read_ahead 1024 sectors
md1 : active raid0 sdl[3] sdk[2] sdb[1] sda[0]
1562845184 blocks 64k chunks
unused devices: <none>
1048576Bytes * 1024 : 158.459MB/s
524288Bytes * 2048 : 164.935MB/s
262144Bytes * 4096 : 173.649MB/s
131072Bytes * 8192 : 174.228MB/s
65536Bytes * 16384 : 178.462MB/s
32768Bytes * 32768 : 177.569MB/s
16384Bytes * 65536 : 177.888MB/s
8192Bytes * 65536 : 173.809MB/s
4096Bytes * 131072 : 172.732MB/s
2048Bytes * 131072 : 165.512MB/s
1024Bytes * 131072 : 150.354MB/s
so looks like the bus is not a bottleneck here. and read ahead really
works here.
i guess the problem is r/w disparity in controller or driver.
thanks guys
ming
On Fri, 2005-07-01 at 09:17 -0400, Ming Zhang wrote:
> On Fri, 2005-07-01 at 08:55 -0400, Guy wrote:
> > I think you should test 2 or more disks at the same time. This
> would prove
> > that your system can or can't move more than about 60MB/s.
>
>
> i tested and seems that 90MB/s is the max here.
>
>
> if i run 2 program copy on 2 disks independently on same card, both of
> them bound at 45MB/s
> if i run 3 program copy on 3 disks independently on same card, both of
> them bound at 27 or 28MB/s so total is still 90MB/s
> if i run 2 program copy on 2 disks but one is on 4 port marvel and
> another is 8 port marvel, then both of the bound at 55MB/s which is
> disk
> limitation.
>
> so i guess the card or bus has problem. i will check bus speed soon.
>
>
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