i also suspect this marvel driver or chip and want to change to another one. but before buying one, maybe i should gather some information on which one is the best 8port or 12 port. :P cpu utilization is not high. < 20% i write a small program that allocate a piece of buffer and write the buffer to device again and again synchronously, no mmap, glibc fwrite, just basic write system call. i can attach the code here if this list allows. i tested to write to /dev/null or a ram disk, pretty fast. ming On Thu, 2005-06-30 at 19:28 -0700, Tyler wrote: > My guess at a glance would be either the Marvel driver is at fault, or > the simple fact of software raid performance... did you monitor the cpu > useage during the tests? even PCI 32bit, 33mhz should be able to hit > 133 Mbytes per second I believe. What are you writing *from* ? dev/zero > or another drive that may not have a read speed high enough to keep up > with what is available? > > Tyler. > > Ming Zhang wrote: > > >I meet some strange low performance when run RAID0 with vanilla kernel > >2.4.27/2.6.11.12. > > > >My box is a 2.8G P4 and 1G RAM. 8 400GB SATA disk and A marvel 8port > >controller. I run marvel 3.4.1 driver. I wrote a small program to write > >device sequentially and SYNCHRONOUSLY. > > > >This is performance of 1 disk. looks fine. > > > > 1048576Bytes * 1024 : 55.466MB/s > > 524288Bytes * 2048 : 55.830MB/s > > 262144Bytes * 4096 : 55.782MB/s > > 131072Bytes * 8192 : 55.567MB/s > > 65536Bytes * 16384 : 55.926MB/s > > 32768Bytes * 32768 : 54.344MB/s > > 16384Bytes * 65536 : 41.415MB/s > > 8192Bytes * 65536 : 26.499MB/s > > 4096Bytes * 65536 : 15.110MB/s > > 2048Bytes * 65536 : 8.422MB/s > > 1024Bytes * 65536 : 4.318MB/s > > > >But when run 2 disk raid0, there is only 10% improvement. > > > >md3 : active raid0 sdb[1] sda[0] > > 781422592 blocks 64k chunks > > 1048576Bytes * 1024 : 67.300MB/s > > 524288Bytes * 2048 : 66.796MB/s > > 262144Bytes * 4096 : 65.728MB/s > > 131072Bytes * 8192 : 65.017MB/s > > 65536Bytes * 16384 : 59.223MB/s > > 32768Bytes * 32768 : 49.766MB/s > > 16384Bytes * 65536 : 39.162MB/s > > 8192Bytes * 65536 : 26.386MB/s > > 4096Bytes * 65536 : 15.084MB/s > > 2048Bytes * 65536 : 8.383MB/s > > 1024Bytes * 65536 : 4.303MB/s > > > >And when use 4 disks, the speed is slower! > >md0 : active raid0 sdh[3] sdg[2] sdf[1] sde[0] > > 1562845184 blocks 64k chunks > > 1048576Bytes * 1024 : 58.032MB/s > > 524288Bytes * 2048 : 56.994MB/s > > 262144Bytes * 4096 : 58.289MB/s > > 131072Bytes * 8192 : 65.999MB/s > > 65536Bytes * 16384 : 59.723MB/s > > 32768Bytes * 32768 : 50.061MB/s > > 16384Bytes * 65536 : 38.689MB/s > > 8192Bytes * 65536 : 26.169MB/s > > 4096Bytes * 65536 : 15.169MB/s > > 2048Bytes * 65536 : 8.378MB/s > > 1024Bytes * 65536 : 4.287MB/s > > > > > >Any hint on this? > > > >* I do not know how to check current PCI bus speed and I am not sure > >whether is limited by that. It is a 64bit card but I am not sure if it > >is run at 66MHZ. Should be, but want to check to make sure. > >* I tested each disk and all disk performs OK. > > > > > >Thanks > > > > > >Ming > > > > > > >
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