On 31/05/17 15:14, Adam Goryachev wrote: > > > On 31/5/17 22:20, CoolCold wrote: >> top stat: >> top - 12:09:03 up 4:55, 2 users, load average: 3.33, 3.18, 2.88 >> Tasks: 487 total, 4 running, 483 sleeping, 0 stopped, 0 zombie >> %Cpu(s): 0.0 us, 4.5 sy, 0.0 ni, 95.3 id, 0.0 wa, 0.0 hi, 0.1 >> si, 0.0 st >> KiB Mem : 13174918+total, 13005539+free, 1191212 used, 502584 >> buff/cache >> KiB Swap: 9764860 total, 9764860 free, 0 used. 13020440+avail >> Mem >> >> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ >> COMMAND >> 22275 root 20 0 0 0 0 R 99.0 0.0 7:01.01 >> md1_raid10 >> >> this cpu usage 99-100% is constant. >> > Sorry, but doesn't that say 95.3% idle? > > Do you have a multi core CPU? Is it multi threaded? What type of CPU is it? > > When running top, press 1, it will then show you each individual core > and the stats for it. > > You might find that creating 10 RAID1 devices, and then using linear > raid to join them together will perform better, from hearsay and memory, > this will allow you to use a CPU for each RAID1, and another CPU for the > linear, so if you had 11 CPU's (or more) then this should get you the > best possible outcome (from a CPU point of view). In fact, if you have > more than one CPU it would help. > For some workloads, a linear concat (which takes no cpu work) of raid1 pairs will be much faster than a raid0 stripe of raid1 pairs. Maybe I am lacking the imagination, but I can't see a use-case where a 20 disk raid10 setup is going to be the most efficient. Raid 0 is good for striped performance, but you would need /massive/ single file streamed reads or writes to cover the loses of latencies on all these disks. And what would you do with all that data? You would quickly saturate 10 Gb network links - there is no point in trying to get data on or off disks much faster than you can use it. > Also, you might want to run a newer kernel, I think there was a lot of > work done on the resync parts to optimise that. You might also prefer to > focus on performance measurements *after* the resync has completed, > since that would be your "normal" status. Though in addition, you should > test performance with one lost disk, and while replacing that disk to > ensure that you are still able to sustain the required load during those > events. > > Regards, > Adam -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
