Hi Alexandre, Yes, it is related to the defect I filed. I think with librbd engine , direct =1 is a noop. It is going through librbd engine not through kernel. Whether it will use cache or not depends upon the rbd_cache flag. This is supposed to be fixed on the latest code but I didn't have time to test this out. It seems the fix is not there in 0.86. Could you please check whether the following commit is there in your branch or not ? 82175ec94acc89dc75da0154f86187fb2e4dbf5e Thanks & Regards Somnath -----Original Message----- From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of Alexandre DERUMIER Sent: Sunday, October 19, 2014 11:02 PM To: ceph-devel@xxxxxxxxxxxxxxx Subject: ceph 0.86 : rbd_cache=true, iops a lot slower on randread 4K Hi, I'm not sure it's related to this bug http://tracker.ceph.com/issues/9513 But, when with this fio-rbd benchmark [global] ioengine=rbd clientname=admin pool=test rbdname=test invalidate=0 rw=randread bs=4k direct=1 numjobs=8 group_reporting=1 size=10G [rbd_iodepth32] iodepth=32 I have around 40000iops (cpu bound on client) with rbd_cache=false vs 13000iops (40%cpu usage on client) with rbd_cache=true (Note that it should be direct ios, so It should bypass the cache). Seem to be a lock or something like that, as the cpu usage is a lot lower too. Is it the expected behavior ? -- 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 ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If the reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify the sender by telephone or e-mail (as shown above) immediately and destroy any and all copies of this message in your possession (whether hard copies or electronically stored copies). ��.n��������+%������w��{.n����z��u���ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
