Hi, I want to propose a session to discuss how we should address large folios in shmem. I have explored the write and fallocate paths [1] (which I will soon post an updated version), but there are additional aspects that need to be covered, such as read and swap paths. I have started an RFC to track blocks for huge pages (aiming to avoid any regressions with large folios) that seems to be going in the wrong direction, according to Hugh's comments. However, there are still some open questions for which I have not yet received a clear answer. In addition, I've been testing tmpfs with kdevops using recent kernels and have encountered some known issues. However, I have not found a clear way to identify them other than through these [3][4] threads. Therefore, having a clear and updated status of all the test profiles and the list of issues would help to provide a better understanding. Note that this aligns with kdevops' goal. Additionally, I recently received some patches from Hugh [5] aimed at addressing the issues in xfstest-dev. Luis has also initiated a thread [6] to collaborate with the 0-day team to track regressions in tmpfs (among other efforts). It would be beneficial to discuss the progress made thus far, potential next steps, and gather insights on this collaborative effort between 0-day and kdevops. Finally, I would like to explore alternative methods for performance testing in tmpfs aside from using fio and/or running kernel build benchmarks. What are the possible approaches for this? Luis recently reported some findings in the last LBS cabal, where XFS on pmem DAX showed significantly better results compared to tmpfs, regardless of whether huge pages were utilized or not. It would be beneficial to share these latest findings and consider implementing methods, possibly integrated into kdevops, to continuously monitor any potential regressions. [1] shmem: high order folios support in write path v1: https://lore.kernel.org/all/20230915095042.1320180-1-da.gomez@xxxxxxxxxxx/ v2: https://lore.kernel.org/all/20230919135536.2165715-1-da.gomez@xxxxxxxxxxx/ v3 (RFC): https://lore.kernel.org/all/20231028211518.3424020-1-da.gomez@xxxxxxxxxxx/ [2] shmem: fix llseek in hugepages RFC: https://lore.kernel.org/all/20240209142901.126894-1-da.gomez@xxxxxxxxxxx/ [3] https://lore.kernel.org/all/alpine.LSU.2.11.2104211723580.3299@eggly.anvils/ [4] https://lore.kernel.org/all/20230713-mgctime-v5-3-9eb795d2ae37@xxxxxxxxxx/ [5] xfstests-dev patches from Hugh: https://gitlab.com/dagmcr/xfstests-dev/-/commits/hughd/tmpfs-fixes/?ref_type=heads [6] https://lore.kernel.org/all/CAB=NE6VRZFn+jxmxADGb3j7fLzBG9rAJ-9RCddEwz0HtwvtHxg@xxxxxxxxxxxxxx/ Are there any other related topics that folks would like to discuss further? Daniel
