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author | Song Liu <songliubraving@fb.com> | 2017-01-24 23:08:23 +0100 |
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committer | Shaohua Li <shli@fb.com> | 2017-02-13 18:17:52 +0100 |
commit | 39b99586b321a9cbd4fe9abb5ea9346d2c4ca9c6 (patch) | |
tree | 8c4d3a516260a209f968c3d1755575433401340e /net/rds | |
parent | md/r5cache: enable chunk_aligned_read with write back cache (diff) | |
download | linux-39b99586b321a9cbd4fe9abb5ea9346d2c4ca9c6.tar.xz linux-39b99586b321a9cbd4fe9abb5ea9346d2c4ca9c6.zip |
md/r5cache: improve journal device efficiency
It is important to be able to flush all stripes in raid5-cache.
Therefore, we need reserve some space on the journal device for
these flushes. If flush operation includes pending writes to the
stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
for the flush out. This reduces the efficiency of journal space.
If we exclude these pending writes from flush operation, we only
need (conf->max_degraded + 1) pages per stripe.
With this patch, when log space is critical (R5C_LOG_CRITICAL=1),
pending writes will be excluded from stripe flush out. Therefore,
we can reduce reserved space for flush out and thus improve journal
device efficiency.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'net/rds')
0 files changed, 0 insertions, 0 deletions