On 2021/3/2 下午4:49, James Page wrote: > Hi Norman > > On Mon, Mar 1, 2021 at 4:38 AM Norman.Kern <norman.kern@xxxxxxx> wrote: > >> Hi, guys >> >> I am testing ceph on bcache devices, I found the performance is not good >> as expected. Does anyone have any best practices for it? Thanks. >> > I've used bcache quite a bit with Ceph with the following configuration > options tweaked > > a) use writeback mode rather than writethrough (which is the default) > > This ensures that the cache device is actually used for write caching > > b) turn off the sequential cutoff > > sequential_cutoff = 0 > > This means that sequential writes will also always go to the cache device > rather than the backing device > > c) disable the congestion read and write thresholds > > congested_read_threshold_us = congested_write_threshold_us = 0 > > The following repository: > > https://git.launchpad.net/charm-bcache-tuning/tree/src/files > > has a python script and systemd configuration todo b) and c) automatically > on all bcache devices on boot; a) we let the provisioning system take care > of. > > HTH I have set the variables described above. Didn't you met the latency problems when cache used increaced 30%? My cache status like this: root@WXS0089:~# cat /sys/block/sda/bcache/priority_stats Unused: 4% Clean: 28% Dirty: 70% Metadata: 0% Average: 551 Sectors per Q: 29197312 Quantiles: [27 135 167 199 230 262 294 326 358 390 422 454 486 517 549 581 613 645 677 709 741 773 804 836 844 847 851 855 860 868 881] > > >> _______________________________________________ >> ceph-users mailing list -- ceph-users@xxxxxxx >> To unsubscribe send an email to ceph-users-leave@xxxxxxx >> > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
 |