On Tue, Jun 08, 2021 at 02:43:40PM +1000, Dave Chinner wrote: > Hi Darrick, > > I've updated the branch and tag for the CIL and log scalability > improvements to fix the CPU hotplug bug that was in the previous > version. The code changes are limited to those, otherwise everything > else in the series is unchanged. > > Please pull from the tag decsribed below. Pulled, thanks! --D > > Cheers, > > Dave. > > The following changes since commit d07f6ca923ea0927a1024dfccafc5b53b61cfecc: > > Linux 5.13-rc2 (2021-05-16 15:27:44 -0700) > > are available in the Git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs.git tags/xfs-cil-scale-2-tag > > for you to fetch changes up to 7017b129e69c1b451fa926f2cac507c4128608dc: > > xfs: expanding delayed logging design with background material (2021-06-08 14:27:46 +1000) > > ---------------------------------------------------------------- > xfs: CIL and log scalability improvements > > Performance improvements are largely documented in the change logs of the > individual patches. Headline numbers are an increase in transaction rate from > 700k commits/s to 1.7M commits/s, and a reduction in fua/flush operations by > 2-3 orders of magnitude on metadata heavy workloads that don't use fsync. > > Summary of series: > > Patches Modifications > ------- ------------- > 1-7: log write FUA/FLUSH optimisations > 8: bug fix > 9-11: Async CIL pushes > 12-25: xlog_write() rework > 26-39: CIL commit scalability > > The log write FUA/FLUSH optimisations reduce the number of cache flushes > required to flush the CIL to the journal. It extends the old pre-delayed logging > ordering semantics required by writing individual transactions to the iclogs out > to cover then CIL checkpoint transactions rather than individual writes to the > iclogs. In doing so, we reduce the cache flush requirements to once per CIL > checkpoint rather than once per iclog write. > > The async CIL pushes fix a pipeline limitation that only allowed a single CIL > push to be processed at a time. This was causing CIL checkpoint writing to > become CPU bound as only a single CIL checkpoint could be pushed at a time. The > checkpoint pipleine was designed to allow multiple pushes to be in flight at > once and use careful ordering of the commit records to ensure correct recovery > order, but the workqueue implementation didn't allow concurrent works to be run. > The concurrent works now extend out to 4 CIL checkpoints running at a time, > hence removing the CPU usage limiations without introducing new lock contention > issues. > > The xlog_write() rework is long overdue. The code is complex, difficult to > understand, full of tricky, subtle corner cases and just generally really hard > to modify. This patchset reworks the xlog_write() API to reduce the processing > overhead of writing out long log vector chains, and factors the xlog_write() > code into a simple, compact fast path along with a clearer slow path to handle > the complex cases. > > The CIL commit scalability patchset removes spinlocks from the transaction > commit fast path. These spinlocks are the performance limiting bottleneck in the > transaction commit path, so we apply a variety of different techniques to do > either atomic. lockless or per-cpu updates of the CIL tracking structures during > commits. This greatly increases the throughput of the the transaction commit > engine, moving the contention point to the log space tracking algorithms after > doubling throughput on 32-way workloads. > > ---------------------------------------------------------------- > Dave Chinner (40): > xfs: log stripe roundoff is a property of the log > xfs: separate CIL commit record IO > xfs: remove xfs_blkdev_issue_flush > xfs: async blkdev cache flush > xfs: CIL checkpoint flushes caches unconditionally > xfs: remove need_start_rec parameter from xlog_write() > xfs: journal IO cache flush reductions > xfs: Fix CIL throttle hang when CIL space used going backwards > xfs: xfs_log_force_lsn isn't passed a LSN > xfs: AIL needs asynchronous CIL forcing > xfs: CIL work is serialised, not pipelined > xfs: factor out the CIL transaction header building > xfs: only CIL pushes require a start record > xfs: embed the xlog_op_header in the unmount record > xfs: embed the xlog_op_header in the commit record > xfs: log tickets don't need log client id > xfs: move log iovec alignment to preparation function > xfs: reserve space and initialise xlog_op_header in item formatting > xfs: log ticket region debug is largely useless > xfs: pass lv chain length into xlog_write() > xfs: introduce xlog_write_single() > xfs:_introduce xlog_write_partial() > xfs: xlog_write() no longer needs contwr state > xfs: xlog_write() doesn't need optype anymore > xfs: CIL context doesn't need to count iovecs > xfs: use the CIL space used counter for emptiness checks > xfs: lift init CIL reservation out of xc_cil_lock > xfs: rework per-iclog header CIL reservation > xfs: introduce CPU hotplug infrastructure > xfs: introduce per-cpu CIL tracking structure > xfs: implement percpu cil space used calculation > xfs: track CIL ticket reservation in percpu structure > xfs: convert CIL busy extents to per-cpu > xfs: Add order IDs to log items in CIL > xfs: convert CIL to unordered per cpu lists > xfs: convert log vector chain to use list heads > xfs: move CIL ordering to the logvec chain > xfs: avoid cil push lock if possible > xfs: xlog_sync() manually adjusts grant head space > xfs: expanding delayed logging design with background material > > Documentation/filesystems/xfs-delayed-logging-design.rst | 361 ++++++++++++++++++++++++++---- > fs/xfs/libxfs/xfs_log_format.h | 4 - > fs/xfs/libxfs/xfs_types.h | 1 + > fs/xfs/xfs_bio_io.c | 35 +++ > fs/xfs/xfs_buf.c | 2 +- > fs/xfs/xfs_buf_item.c | 39 ++-- > fs/xfs/xfs_dquot_item.c | 2 +- > fs/xfs/xfs_file.c | 20 +- > fs/xfs/xfs_inode.c | 10 +- > fs/xfs/xfs_inode_item.c | 18 +- > fs/xfs/xfs_inode_item.h | 2 +- > fs/xfs/xfs_linux.h | 2 + > fs/xfs/xfs_log.c | 1015 +++++++++++++++++++++++++++++++++++++++--------------------------------------------- > fs/xfs/xfs_log.h | 66 ++---- > fs/xfs/xfs_log_cil.c | 804 ++++++++++++++++++++++++++++++++++++++++++++++++------------------ > fs/xfs/xfs_log_priv.h | 123 ++++++----- > fs/xfs/xfs_super.c | 52 ++++- > fs/xfs/xfs_super.h | 1 - > fs/xfs/xfs_sysfs.c | 1 + > fs/xfs/xfs_trace.c | 1 + > fs/xfs/xfs_trans.c | 18 +- > fs/xfs/xfs_trans.h | 5 +- > fs/xfs/xfs_trans_ail.c | 11 +- > fs/xfs/xfs_trans_priv.h | 3 +- > include/linux/cpuhotplug.h | 1 + > 25 files changed, 1632 insertions(+), 965 deletions(-) > > -- > Dave Chinner > david@xxxxxxxxxxxxx
