On Thu, Jul 06, 2023 at 02:39:08PM -0700, Omar Sandoval wrote: > On Tue, Jun 20, 2023 at 02:32:10PM -0700, Omar Sandoval wrote: > > Hello, > > > > Our distributed storage system uses XFS's realtime device support as a > > way to split an XFS filesystem between an SSD and an HDD -- we configure > > the HDD as the realtime device so that metadata goes on the SSD and data > > goes on the HDD. > > > > We've been running this in production for a few years now, so we have > > some fairly fragmented filesystems. This has exposed various CPU > > inefficiencies in the realtime allocator. These became even worse when > > we experimented with using XFS_XFLAG_EXTSIZE to force files to be > > allocated contiguously. > > > > This series adds several optimizations that don't change the realtime > > allocator's decisions, but make them happen more efficiently, mainly by > > avoiding redundant work. We've tested these in production and measured > > ~10% lower CPU utilization. Furthermore, it made it possible to use > > XFS_XFLAG_EXTSIZE to force contiguous allocations -- without these > > patches, our most fragmented systems would become unresponsive due to > > high CPU usage in the realtime allocator, but with them, CPU utilization > > is actually ~4-6% lower than before, and disk I/O utilization is 15-20% > > lower. > > > > Patches 2 and 3 are preparations for later optimizations; the remaining > > patches are the optimizations themselves. > > > > This is based on Linus' tree as of today (commit > > 692b7dc87ca6d55ab254f8259e6f970171dc9d01). > > > > Thanks! > > > > Omar Sandoval (6): > > xfs: cache last bitmap block in realtime allocator > > xfs: invert the realtime summary cache > > xfs: return maximum free size from xfs_rtany_summary() > > xfs: limit maxlen based on available space in > > xfs_rtallocate_extent_near() > > xfs: don't try redundant allocations in xfs_rtallocate_extent_near() > > xfs: don't look for end of extent further than necessary in > > xfs_rtallocate_extent_near() > > > > fs/xfs/libxfs/xfs_rtbitmap.c | 173 ++++++++++++++-------------- > > fs/xfs/xfs_mount.h | 6 +- > > fs/xfs/xfs_rtalloc.c | 215 ++++++++++++++++------------------- > > fs/xfs/xfs_rtalloc.h | 28 +++-- > > 4 files changed, 207 insertions(+), 215 deletions(-) > > Gentle ping. Sorry, I haven't had time to get to this yet. I've still got a couple more bug reports to work through before I can really start thinking about looking at anything else.. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
