Hi all, After some discussion on IRC with Dave, we came to the conclusion that our background workqueue behavior could use some tweaking. Kernel worker threads that scan the filesystem and/or run their own transactions more closely fit the definition of an unbound workqueue -- the work items can take a long time, they don't have much in common with the submitter thread, the submitter isn't waiting hotly for a response, and we the process scheduler should deal with scheduling them. Furthermore, we don't want to place artificial limits on workqueue scaling because that can leave unused capacity while we're blocking (pwork is currently used for mount time quotacheck). Therefore, we switch pwork to use an unbound workqueue, and now we let the workqueue code figure out the relevant concurrency. The final tweak is to enable WQ_SYSFS on all workqueues so that we can monitor their concurrency management (or lack thereof) via sysfs. If you're going to start using this mess, you probably ought to just pull from my git trees, which are linked below. This is an extraordinary way to destroy everything. Enjoy! Comments and questions are, as always, welcome. --D kernel git tree: https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=workqueue-speedups-5.12 --- fs/xfs/xfs_iwalk.c | 5 +---- fs/xfs/xfs_log.c | 4 ++-- fs/xfs/xfs_mru_cache.c | 2 +- fs/xfs/xfs_pwork.c | 21 ++------------------- fs/xfs/xfs_pwork.h | 1 - fs/xfs/xfs_super.c | 23 ++++++++++++++--------- 6 files changed, 20 insertions(+), 36 deletions(-)
