Hi, my 2cent, maybe with lower range (like 100MB) of random io, you have more chance to aggregate them in 4MB block ? I'll do some tests today with my 15K drives ----- Mail original ----- De: "Stefan Priebe" <s.priebe@xxxxxxxxxxxx> À: "Mark Nelson" <mark.nelson@xxxxxxxxxxx> Cc: "Sage Weil" <sage@xxxxxxxxxxx>, ceph-devel@xxxxxxxxxxxxxxx Envoyé: Dimanche 1 Juillet 2012 23:27:30 Objet: Re: speedup ceph / scaling / find the bottleneck Am 01.07.2012 23:13, schrieb Mark Nelson: > On 7/1/12 4:01 PM, Stefan Priebe wrote: >> Hello list, >> Hello sage, >> >> i've made some further tests. >> >> Sequential 4k writes over 200GB: 300% CPU usage of kvm process 34712 iops >> >> Random 4k writes over 200GB: 170% CPU usage of kvm process 5500 iops >> >> When i make random 4k writes over 100MB: 450% CPU usage of kvm process >> and !! 25059 iops !! >> > When you say 100MB vs 200GB, do you mean the total amount of data that > is written for the test? Yes/No, it is the max amount of data written but for random I/O it is also the range like random block device position between 0 and X where to write the 4K block. > Also, are these starting out on a fresh > filesystem? Yes, 5 Min old in this case ;-) Stefan -- 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 -- -- Alexandre D e rumier Ingénieur Systèmes et Réseaux Fixe : 03 20 68 88 85 Fax : 03 20 68 90 88 45 Bvd du Général Leclerc 59100 Roubaix 12 rue Marivaux 75002 Paris -- 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
