Hi Ming, Thanks and I ran another block device read test by doing: sync; time dd if=/dev/evms/.nodes/md/md3 of=/dev/null bs=1024k count=1024 AND sync; time dd if=/dev/evms/volume1 of=/dev/null bs=1024k count=1024 the /dev/evms/volume1 is a evms volume on top of /dev/evms/.nodes/md/md3 And the results are (real/user/sys): /dev/evms/.nodes/md/md3: 29.757s/0.020s/15.861s /dev/evms/volume1: 41.697s/0.004s/25.586s /dev/evms/volume1 took 12 seconds more to read the same amount of blocks. Compare to 29.757 seconds it's about 40% more. Can we said it's introduced by device mapper? Ken -----Original Message----- From: Ming Zhang [mailto:mingz@xxxxxxxxxxx] Sent: Friday, March 10, 2006 8:59 AM To: ken.hwang@xxxxxxxxx; device-mapper development Subject: Re: 2.6 device mapper performance? u have too many chances here. so hard to blame any one. suggest u to test it one by one if possible. for example, have same box run 2.4 and 2.6, test performance on volume first before run xfs, and samba. ming On Wed, 2006-03-08 at 16:49 -0800, Ken Hwang wrote: > Hi, > > I'm not sure I should ask this question here, if this is not the place then > I apologize. I have a home made NAS with Linux. I use evms to create volume, > put xfs on top of it, and then use samba to share it with Windows clients. > When I was using kernel 2.4 with all the needed patches I could get netbench > 106Mbps with 4 clients, and 95Mbps with 8 clients. Recently I upgraded the > same hardware to kernel 2.6 (I also upgraded the related application such as > samba, xfs utility, and dmsetup accordingly). Then I ran netbench again and > got 80Mbps with 4 clients, 53Mbps with 8 clients. Which drop almost 80% (95 > vs 53) in 8 clients case. > > I then make and mount xfs on another raid5 (which uses the same disk but on > different partitions) and found it got better performance (95Mbps with 4 > clients, 85Mbps with 8 clients). In brief: > xfs volume on raid5 md/md1 on sda6/sdb6/sdc6/sdd6 netbench: 95/85Mbps > xfs volume on EVMS volume /dev/evms/volume1 on raid5 md/md3 on > sda8/sdb8/sdc8/sdd8: 80/53Mbps > > Do you think the slow down (85 to 53Mbps) was caused by device mapper? > Please advice. > > Ken > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.375 / Virus Database: 268.2.0/276 - Release Date: 3/7/2006 > > -- > > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.2.1/278 - Release Date: 3/9/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 268.2.1/279 - Release Date: 3/10/2006 -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
