9p: Performance improvements for build workloads#1316
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vfsci-bot[bot] wants to merge 4 commits intovfs.base.cifrom
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9p: Performance improvements for build workloads#1316vfsci-bot[bot] wants to merge 4 commits intovfs.base.cifrom
vfsci-bot[bot] wants to merge 4 commits intovfs.base.cifrom
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Not caching negative dentries can result in poor performance for workloads that repeatedly look up non-existent paths. Each such lookup triggers a full 9P transaction with the server, adding unnecessary overhead. A typical example is source compilation, where multiple cc1 processes are spawned and repeatedly search for the same missing header files over and over again. This change enables caching of negative dentries, so that lookups for known non-existent paths do not require a full 9P transaction. The cached negative dentries are retained for a configurable duration (expressed in milliseconds), as specified by the ndentry_timeout field in struct v9fs_session_info. If set to -1, negative dentries are cached indefinitely. This optimization reduces lookup overhead and improves performance for workloads involving frequent access to non-existent paths. Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Introduce a new mount option, negtimeout, for v9fs that allows users to specify how long negative dentries are retained in the cache. The retention time can be set in milliseconds (e.g. negtimeout=10000 for a 10secs retention time) or a negative value (e.g. negtimeout=-1) to keep negative entries until the buffer cache management removes them. For consistency reasons, this option should only be used in exclusive or read-only mount scenarios, aligning with the cache=loose usage. Signed-off-by: Remi Pommarel <repk@triplefau.lt>
For cache=loose mounts, set the default negative dentry cache retention time to 24 hours. Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Currently, when cache=loose is enabled, file reads are cached in the page cache, but symlink reads are not. This patch allows the results of p9_client_readlink() to be stored in the page cache, eliminating the need for repeated 9P transactions on subsequent symlink accesses. This change improves performance for workloads that involve frequent symlink resolution. Signed-off-by: Remi Pommarel <repk@triplefau.lt>
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Series: https://patchwork.kernel.org/project/linux-fsdevel/list/?series=1089492
Submitter: Remi Pommarel
Version: 5
Patches: 4/4
Message-ID:
<cover.1777923233.git.repk@triplefau.lt>Base: vfs.base.ci
Lore: https://lore.kernel.org/linux-fsdevel/cover.1777923233.git.repk@triplefau.lt
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