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README: "btrfs: improve delayed refs iterations" has been merged into v4.10-rc1

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Signed-off-by: Zygo Blaxell <bees@furryterror.org>
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Zygo Blaxell 2017-01-09 00:02:23 -05:00
parent cf04fb17de
commit 6980935463
1 changed files with 10 additions and 13 deletions
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README.md
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@ -234,22 +234,19 @@ Bug fixes (sometimes included in older LTS kernels):
* 4.5: use-after-free in the `FILE_EXTENT_SAME` ioctl used by Bees.
* 4.7: *slow backref* bug no longer triggers a softlockup panic. It still
too long to resolve a block address to a root/inode/offset triple.
Fixed bugs not yet integrated in mainline Linux:
* 7f8e406 ("btrfs: improve delayed refs iterations"): significantly
reduces the CPU time cost of the LOGICAL_INO ioctl (from 30-70% of
bees running time to under 5%).
* 4.10-rc1: reduced CPU time cost of the LOGICAL_INO ioctl and dedup
backref processing in general.
Unfixed kernel bugs (as of 4.5.7) with workarounds in Bees:
* *slow backref*: If the number of references to a single shared extent
within a single file grows above a few thousand, the kernel consumes CPU
for up to 40 uninterruptible minutes while holding various locks that
block access to the filesystem. Bees avoids this bug by measuring the
time the kernel spends performing certain operations and permanently
blacklisting any extent or hash where the kernel starts to get slow.
Inside Bees, such blocks are marked as 'toxic' hash/block addresses.
* *slow backrefs* (aka toxic extents): If the number of references to a
single shared extent within a single file grows above a few thousand,
the kernel consumes CPU for minutes at a time while holding various
locks that block access to the filesystem. Bees avoids this bug by
measuring the time the kernel spends performing certain operations
and permanently blacklisting any extent or hash where the kernel
starts to get slow. Inside Bees, such blocks are marked as 'toxic'
hash/block addresses.
* `LOGICAL_INO` output is arbitrarily limited to 2730 references
even if more buffer space is provided for results. Once this number