On 15.09.23 11:51, Daniel Gomez wrote:
This series add support for high order folios in shmem write path. This is a continuation of the shmem work from Luis here [1] following Matthew Wilcox's suggestion [2] regarding the path to take for the folio allocation order calculation. [1] RFC v2 add support for blocksize > PAGE_SIZE https://lore.kernel.org/all/ZHBowMEDfyrAAOWH@xxxxxxxxxxxxxxxxxxxxxx/T/#md3e93ab46ce2ad9254e1eb54ffe71211988b5632 [2] https://lore.kernel.org/all/ZHD9zmIeNXICDaRJ@xxxxxxxxxxxxxxxxxxxx/ Patches have been tested and sent from next-230911. They do apply cleanly to the latest next-230914. fsx and fstests has been performed on tmpfs with noswap with the following results: - fsx: 2d test, 21,5B - fstests: Same result as baseline for next-230911 [3][4][5] [3] Baseline next-230911 failures are: generic/080 generic/126 generic/193 generic/633 generic/689 [4] fstests logs baseline: https://gitlab.com/-/snippets/3598621 [5] fstests logs patches: https://gitlab.com/-/snippets/3598628 There are at least 2 cases/topics to handle that I'd appreciate feedback. 1. With the new strategy, you might end up with a folio order matching HPAGE_PMD_ORDER. However, we won't respect the 'huge' flag anymore if THP is enabled. 2. When the above (1.) occurs, the code skips the huge path, so xa_find with hindex is skipped.
Similar to large anon folios (but different to large non-shmem folios in the pagecache), this can result in memory waste.
We discussed that topic in the last bi-weekly mm meeting, and also how to eventually configure that for shmem.
Refer to of a summary. [1] [1] https://lkml.kernel.org/r/4966f496-9f71-460c-b2ab-8661384ce626@xxxxxxx -- Cheers, David / dhildenb
