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| author |   Shaohua Li <shli@kernel.org> | 2013-12-31 11:38:27 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2014-01-30 12:57:25 -0700 |
| commit | d835502f3dacad1638d516ab156d66f0ba377cf5 (patch) | |
| tree | 1a82543b7c14120251a4bceaa08f5cc9f86ecf43 /block/blk-flush.c | |
| parent | Merge branch 'for-3.14/drivers' of git://git.kernel.dk/linux-block (diff) | |
| download | wireguard-linux-d835502f3dacad1638d516ab156d66f0ba377cf5.tar.xz wireguard-linux-d835502f3dacad1638d516ab156d66f0ba377cf5.zip | |
percpu_ida: fix a live lock
steal_tags only happens when free tags is more than half of the total
tags. This is too strict and can cause live lock. I found that if one
cpu has free tags, but other cpu can't steal (thread is bound to
specific cpus), threads which want to allocate tags are always
sleeping. I found this when I run next patch, but this could happen
without it I think.
I did performance test too with null_blk. Two cases (each cpu has enough
percpu tags, or total tags are limited), no performance changes were
observed.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-flush.c')
0 files changed, 0 insertions, 0 deletions