On Sat, 17 Mar 2012, Andrey Korolyov wrote: > Hi, > > I`ve did some performance tests at the following configuration: > > mon0, osd0 and mon1, osd1 - two twelve-core r410 with 32G ram, mon2 - > dom0 with three dedicated cores and 1.5G, mostly idle. First three > disks on each r410 arranged into raid0 and holds osd data when fourth > holds os and osd` journal partition, all ceph-related stuff mounted on > the ext4 without barriers. > > Firstly, I`ve noticed about a difference of benchmark performance and > write speed through rbd from small kvm instance running on one of > first two machines - when bench gave me about 110Mb/s, writing zeros > to raw block device inside vm with dd was at top speed about 45 mb/s, > for vm`fs (ext4 with default options) performance drops to ~23Mb/s. > Things get worse, when I`ve started second vm at second host and tried > to continue same dd tests simultaneously - performance fairly divided > by half for each instance :). Enabling jumbo frames, playing with cpu > affinity for ceph and vm instances and trying different TCP congestion > protocols gave no effect at all - with DCTCP I have slightly smoother > network load graph and that`s all. > > Can ml please suggest anything to try to improve performance? Can you try setting rbd writeback window = 8192000 or similar, and see what kind of effect that has? I suspect it'll speed up dd; I'm less sure about ext3. Thanks! sage > > ceph-0.43, libvirt-0.9.8, qemu-1.0.0, kernel 3.2 > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
