On Fri, 27 Apr 2018 11:06:46 +0200 Linus Lüssing <linus.luessing@xxxxxxxxx> wrote: > Hi! > > When running a RAID check via: > > $ echo check > /sys/block/md127/md/sync_action > > The underlying system, especially a Linux container, becomes barely > usable. Webservers run into timeouts etc. > > In top I see that md127_raid6 is run at priority 20. However some > (10+) other kworker processes do not and run at priority -20 and > consume a siginificant amount of sys CPU usage while the RAID check > is in progress. > > Are there any suggested ways to tune/fix the priorization issue > I'm having? > > The setup I'm having here is pretty low-cost, low-power. A Pi3 > with 64 bit kernel, 5 SATA drives connected via USB, configured as > RAID6. Raspberry Pi 3 has a quad-core CPU, do you actually see 400% CPU load from resync? IIRC it wasn't this multi-threaded. And my guess is that you suffer not from the CPU load, but from contention for access to HDD between user tasks and the resync/check process. Try this patch: md: allow faster resync only on non-rotational media https://www.spinics.net/lists/raid/msg60722.html -- With respect, Roman -- 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
