Cool, thanks! On Wed, Aug 17, 2016 at 5:39 PM, Jason Dillaman <jdillama@xxxxxxxxxx> wrote: > Wow, thanks for elevating this issue to my attention. This is > definitely a bug that was introduced accidentally during all the > internal refactoring work in support the new journaling feature. I > will get a fix up for review today against the master branch and we > can hopefully include it in the next Jewel point release as well. > > Thanks, > Jason > > On Wed, Aug 17, 2016 at 11:03 AM, Mark Korondi <korondi.mark@xxxxxxxxx> wrote: >> Hi all, >> >> my team struggles with enabling rbd caching with Jewel clusters. In >> Hammer, we successfully use rbd caching with the `writethrough until >> flush` directive set to true and we get expected IOPS numbers. >> However, with the same configuration using Jewel, IOPS drops; after >> analyzing logs it seems to us that the writeback caching mechanism >> never gets enabled regardless of flush request is being sent. >> >> We found a bug entry describing an issue similar to ours: >> http://tracker.ceph.com/issues/16654 >> >> As our note #3 says, we concluded that it seems that the imagecontext >> user_flushed() signal is missing from the later version, therefore the >> caching mechanism will never be switched to writeback. >> >> Our questions are these: >> 1) is this change intentional and one needs to configure their >> environment differently? If yes, how? >> 2) documentation states that this workaround is only needed with older >> virtio kernel driver too old. With newer kernels, what would be the >> possible implications of setting `rbd cache writethrough until flush` >> to false? Is my understanding correct that this virtio driver version >> what matters is that is *in the VM*? >> >> Thanks, >> Mark > > > > -- > Jason -- 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
