setup a bitter value for read_ahead_kb ? I tested with 256 MB read ahead cache (
From: ceph-users-boun...@lists.ceph.com [mailto:ceph-users-boun...@lists.ceph.com] On Behalf Of ???? ??????? Sent: Friday, February 07, 2014 10:55 AM To: Konrad Gutkowski Cc: ceph-users@lists.ceph.com Subject: Re: [ceph-users] RBD+KVM problems with sequential read echo "noop">/sys/block/vda/queue/scheduler echo "1000" >/sys/block/vda/queue/nr_requests echo "8192">/sys/block/vda/queue/read_ahead_kb [root@nfs tmp]# dd if=test of=/dev/null 39062500+0 records in 39062500+0 records out 20000000000 bytes (20 GB) copied, 244.024 s, 82.0 MB/s Changing these parameters are not affected... Are there other ideas on this problem? Thank you. 2014-02-07 Konrad Gutkowski <konrad.gutkow...@ffs.pl<mailto:konrad.gutkow...@ffs.pl>>: Hi, W dniu 07.02.2014 o 08:14 Ирек Фасихов <malm...@gmail.com<mailto:malm...@gmail.com>> pisze: [...] Why might such a low speed sequential read? Do ideas on this issue? Iirc you need to set your readahead for the device higher (inside the vm) to compensate for network rtt. blockdev --setra x /dev/vda Thanks. -- С уважением, Фасихов Ирек Нургаязович Моб.: +79229045757 Regards, Konrad Gutkowski _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com<mailto:ceph-users@lists.ceph.com> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com -- С уважением, Фасихов Ирек Нургаязович Моб.: +79229045757
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