On Wed, Apr 24 2019 at 3:45pm -0400, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Fri, Apr 19 2019 at 10:40am -0400, > Ryan Norwood <ryan.p.norwood@xxxxxxxxx> wrote: > > > We have been using dm-thin layered above VDO and have noticed that our > > performance is not optimal for large sequential writes as max_sectors_kb > > and max_hw_sectors_kb for all thin devices are set to 4k due to the VDO > > layer beneath. > > This effectively eliminates the performance optimizations for sequential > > writes to skip both zeroing and COW overhead when a write fully overlaps a > > thin chunk as all bios are split into 4k which always be less than the 64k > > thin chunk minimum. > > Is this known behavior? Is there any way around this issue? > > Are you creating the thin-pool to use a 4K thinp blocksize? If not, > I'll have to look to see why the block core's block limits stacking > would impose these limits of the underlying data device. > > > We are using RHEL 7.5 with kernel 3.10.0-862.20.2.el7.x86_64. > > OK, please let me know what the thin-pool's blocksize is. Nevermind, I see you have done so in another portion of this thread. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
