Hi all, This is a first (non-rfc) pass at the XFS extent allocation rework. This series aims to 1.) improve the near mode allocation algorithm to have better breakdown characteristics by taking advantage of locality optimized cntbt lookups instead of relying so heavily on bnobt scans and 2.) refactor the remaining allocation modes to reuse similar code and reduce duplication. Patches 1 and 2 are cleanups to the small allocation mode fallback function. Patch 3 reworks the near mode allocation algorithm as noted above and introduces reusable infrastructure. Patches 4 and 5 rework the exact and by-size allocation modes respectively. Patch 6 removes the unused bits of the small allocation mode and refactors the remaining code into an AGFL allocation helper. With regard to regression testing, this series survives multiple fstests runs with various geometries, such as defaults, abnormally high AG counts, and nonstandard block sizes. This also survives several days of iterative, concurrent stress loads of fsstress, fs_mark and growfiles (xfstests/ltp/growfiles.c) to repeatedly run a filesystem out of space without any explosions. With regard to performance, I have a user provided metadump image with heavy free space fragmentation that demonstrates pathological allocation behavior. An fs_mark test against this filesystem image shows an improvement from 30-100 files/second to 600-800 f/s. On newly created filesystems, I ran a filebench workload of 16 file creator threads creating a mix of small (4k-1mb), medium (10mb-100mb) and larger (500mb-1g) files and issuing fsyncs which shows comparable performance and post-test free space properties with and without the patchset. Finally, I've also run some ad hoc tests with fs_mark and fio (fallocate and aio engines doing random writes) and observe no notable regressions with these patches. I may continue to experiment with filebench but so far I've not seen anything that shows significant regressions. Let me know if anybody would like to see test output or configuration details or whatnot from any of that, or would like me to run any additional tests, etc. Thoughts, reviews, flames appreciated. Brian v1: - Continued development (various fixes, refinements) on generic bits and near mode implementation. - Added patches 4-6 to refactor exact, by-size and small allocation modes. rfcv2: https://marc.info/?l=linux-xfs&m=155197946630582&w=2 - Dropped spurious initial refactoring. - Added minlen functionality. - Properly tied into near alloc path. - General refactoring and cleanups. rfcv1: https://marc.info/?l=linux-xfs&m=154479089914351&w=2 Brian Foster (6): xfs: refactor small allocation helper to skip cntbt attempt xfs: always update params on small allocation xfs: use locality optimized cntbt lookups for near mode allocations xfs: refactor exact extent allocation mode xfs: refactor by-size extent allocation mode xfs: replace small allocation logic with agfl only logic fs/xfs/libxfs/xfs_alloc.c | 1375 +++++++++++++++---------------------- fs/xfs/xfs_trace.h | 38 +- 2 files changed, 595 insertions(+), 818 deletions(-) -- 2.17.2
