I can use the following command to change parameter, for example as the following, but not sure whether it will work.
ceph --admin-daemon /var/run/ceph/ceph-mon.openpower-0.asok config set rbd_readahead_disable_after_bytes 0 2016-03-01 15:07 GMT+08:00 Tom Christensen <[email protected]>: > If you are mapping the RBD with the kernel driver then you're not using > librbd so these settings will have no effect I believe. The kernel driver > does its own caching but I don't believe there are any settings to change > its default behavior. > > > On Mon, Feb 29, 2016 at 9:36 PM, Shinobu Kinjo <[email protected]> wrote: > >> You may want to set "ioengine=rbd", I guess. >> >> Cheers, >> >> ----- Original Message ----- >> From: "min fang" <[email protected]> >> To: "ceph-users" <[email protected]> >> Sent: Tuesday, March 1, 2016 1:28:54 PM >> Subject: [ceph-users] rbd cache did not help improve performance >> >> Hi, I set the following parameters in ceph.conf >> >> [client] >> rbd cache=true >> rbd cache size= 25769803776 >> rbd readahead disable after byte=0 >> >> >> map a rbd image to a rbd device then run fio testing on 4k read as the >> command >> ./fio -filename=/dev/rbd4 -direct=1 -iodepth 64 -thread -rw=read >> -ioengine=aio -bs=4K -size=500G -numjobs=32 -runtime=300 -group_reporting >> -name=mytest2 >> >> Compared the result with setting rbd cache=false and enable cache model, >> I did not see performance improved by librbd cache. >> >> Is my setting not right, or it is true that ceph librbd cache will not >> have benefit on 4k seq read? >> >> thanks. >> >> >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >
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