This patch series attempts to improve write performance with RWF_DONTCACHE. The main justification and benchmarks for the series are in patch #2.
This version implements a scheme that Jan Kara and Christoph Hellwig suggested during review of the earlier series: after a DONTCACHE write, kick the flusher thread to do an amount of writeback proportional to the amount written, but don't target any particular inode or pages when doing writeback. The second patch in the series has a summary of the benchmark results. This seems to work as well or better than the earlier approaches. The benchmarks I used are in the last two patches. I'm not sure if we want to merge those into the tree as they are (mostly) AI slop. There is probably a better tool for this out there. Signed-off-by: Jeff Layton <[email protected]> --- Changes in v3: - Track dirty DONTCACHE pages in the VM - Have flusher write back a proportional number of pages after DONTCACHE write - Link to v2: https://lore.kernel.org/r/[email protected] Changes in v2: - kick flusher thread instead of initiating writeback inline - add mechanism to run 'perf lock' around the testcases - Link to v1: https://lore.kernel.org/r/[email protected] --- Jeff Layton (4): mm: add NR_DONTCACHE_DIRTY node page counter mm: kick writeback flusher for IOCB_DONTCACHE with targeted dirty tracking testing: add nfsd-io-bench NFS server benchmark suite testing: add dontcache-bench local filesystem benchmark suite fs/fs-writeback.c | 60 +++ include/linux/backing-dev-defs.h | 2 + include/linux/fs.h | 6 +- include/linux/mmzone.h | 1 + include/trace/events/writeback.h | 3 +- mm/filemap.c | 6 +- mm/page-writeback.c | 7 + mm/vmstat.c | 1 + .../dontcache-bench/fio-jobs/lat-reader.fio | 12 + .../dontcache-bench/fio-jobs/multi-write.fio | 9 + .../dontcache-bench/fio-jobs/noisy-writer.fio | 12 + .../testing/dontcache-bench/fio-jobs/rand-read.fio | 13 + .../dontcache-bench/fio-jobs/rand-write.fio | 13 + .../testing/dontcache-bench/fio-jobs/seq-read.fio | 13 + .../testing/dontcache-bench/fio-jobs/seq-write.fio | 13 + .../dontcache-bench/scripts/parse-results.sh | 238 +++++++++ .../dontcache-bench/scripts/run-benchmarks.sh | 562 ++++++++++++++++++++ .../testing/nfsd-io-bench/fio-jobs/lat-reader.fio | 15 + .../testing/nfsd-io-bench/fio-jobs/multi-write.fio | 14 + .../nfsd-io-bench/fio-jobs/noisy-writer.fio | 14 + tools/testing/nfsd-io-bench/fio-jobs/rand-read.fio | 15 + .../testing/nfsd-io-bench/fio-jobs/rand-write.fio | 15 + tools/testing/nfsd-io-bench/fio-jobs/seq-read.fio | 14 + tools/testing/nfsd-io-bench/fio-jobs/seq-write.fio | 14 + .../testing/nfsd-io-bench/scripts/parse-results.sh | 238 +++++++++ .../nfsd-io-bench/scripts/run-benchmarks.sh | 591 +++++++++++++++++++++ .../testing/nfsd-io-bench/scripts/setup-server.sh | 94 ++++ 27 files changed, 1989 insertions(+), 6 deletions(-) --- base-commit: 27d128c1cff64c3b8012cc56dd5a1391bb4f1821 change-id: 20260401-dontcache-5811efd7eaf3 Best regards, -- Jeff Layton <[email protected]>
