f2fs: flush plug periodically during GC to maximize readahead effect

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During the garbage collection process, F2FS submits readahead I/Os for
valid blocks. However, since the GC loop runs within a single plug scope
without intermediate flushing, these readahead I/Os often accumulate in
the block layer's plug list instead of being dispatched to the device
immediately.

Consequently, when the GC thread attempts to lock the page later, the
I/O might not have completed (or even started), leading to a "read try
and wait" scenario. This negates the benefit of readahead and causes
unnecessary delays in GC latency.

This patch addresses this issue by introducing an intermediate
blk_finish_plug() and blk_start_plug() pair within the GC loop. This
forces the dispatch of pending I/Os, ensuring that readahead pages are
fetched in time, thereby reducing GC latency.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

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Daeho Jeong 2025-12-30 09:38:45 -08:00 • committed by Jaegeuk Kim

parent 572b1c6f2a

commit 7ec199117c

1 changed files with 13 additions and 6 deletions

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fs/f2fs/gc.c

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