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3598 want to dtrace when errors are generated in zfs
Reviewed by: Dan Kimmel <[email protected]>
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Approved by: Garrett D'Amore <[email protected]>
References:
https://www.illumos.org/issues/3598
illumos/illumos-gate@be6fd75a69ae679453d9cda5bff3326111e6d1ca
Ported-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #1775
Porting notes:
1. include/sys/zfs_context.h has been modified to render some new
macros inert until dtrace is available on Linux.
2. Linux-specific changes have been adapted to use SET_ERROR().
3. I'm NOT happy about this change. It does nothing but ugly
up the code under Linux. Unfortunately we need to take it to
avoid more merge conflicts in the future. -Brian
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3578 transferring the freed map to the defer map should be constant time
3579 ztest trips assertion in metaslab_weight()
Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: Dan Kimmel <[email protected]>
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Reviewed by: Richard Elling <[email protected]>
Approved by: Dan McDonald <[email protected]>
References:
https://www.illumos.org/issues/3578
https://www.illumos.org/issues/3579
illumos/illumos-gate@9eb57f7f3fbb970d4b9b89dcd5ecf543fe2414d5
Ported-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
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3552 condensing one space map burns 3 seconds of CPU in spa_sync()
thread (fix race condition)
References:
https://www.illumos.org/issues/3552
illumos/illumos-gate@03f8c366886542ed249a15d755ae78ea4e775d9d
Ported-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Porting notes:
This fixes an upstream regression that was introduced in commit
zfsonlinux/zfs@e51be06697762215dc3b679f8668987034a5a048, which
ported the Illumos 3552 changes. This fix was added to upstream
rather quickly, but at the time of the port, no one spotted it and
the race was rare enough that it passed our regression tests. I
discovered this when comparing our metaslab.c to the illumos
metaslab.c.
Without this change it is possible for metaslab_group_alloc() to
consume a large amount of cpu time. Since this occurs under a
mutex in a rcu critical section the kernel will log this to the
console as a self-detected cpu stall as follows:
INFO: rcu_sched self-detected stall on CPU { 0}
(t=60000 jiffies g=11431890 c=11431889 q=18271)
Closes #1687
Closes #1720
Closes #1731
Closes #1747
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3464 zfs synctask code needs restructuring
Reviewed by: Dan Kimmel <[email protected]>
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Approved by: Garrett D'Amore <[email protected]>
References:
https://www.illumos.org/issues/3464
illumos/illumos-gate@3b2aab18808792cbd248a12f1edf139b89833c13
Ported-by: Tim Chase <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1495
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3552 condensing one space map burns 3 seconds of CPU in spa_sync() thread
3564 spa_sync() spends 5-10% of its time in metaslab_sync() (when not condensing)
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Dan Kimmel <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Approved by: Richard Lowe <[email protected]>
References:
illumos/illumos-gate@16a4a8074274d2d7cc408589cf6359f4a378c861
https://www.illumos.org/issues/3552
https://www.illumos.org/issues/3564
Ported-by: Tim Chase <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1513
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3006 VERIFY[S,U,P] and ASSERT[S,U,P] frequently check if first
argument is zero
Reviewed by Matt Ahrens <[email protected]>
Reviewed by George Wilson <[email protected]>
Approved by Eric Schrock <[email protected]>
References:
illumos/illumos-gate@fb09f5aad449c97fe309678f3f604982b563a96f
https://illumos.org/issues/3006
Requires:
zfsonlinux/spl@1c6d149feb4033e4a56fb987004edc5d45288bcb
Ported-by: Tim Chase <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1509
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3329 spa_sync() spends 10-20% of its time in spa_free_sync_cb()
3330 space_seg_t should have its own kmem_cache
3331 deferred frees should happen after sync_pass 1
3335 make SYNC_PASS_* constants tunable
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Reviewed by: Eric Schrock <[email protected]>
Reviewed by: Richard Lowe <[email protected]>
Reviewed by: Dan McDonald <[email protected]>
Approved by: Eric Schrock <[email protected]>
References:
illumos/illumos-gate@01f55e48fb4d524eaf70687728aa51b7762e2e97
https://www.illumos.org/issues/3329
https://www.illumos.org/issues/3330
https://www.illumos.org/issues/3331
https://www.illumos.org/issues/3335
Ported-by: Brian Behlendorf <[email protected]>
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Enabling metaslab debugging will prevent space maps from being
automatically unloaded. This can significantly increase the
memory footprint but being able to dynamically control this is
helpful for debugging and certain performance testing.
Signed-off-by: Brian Behlendorf <[email protected]>
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Currently, ZIL blocks are spread over vdevs using hint block pointers
managed by the ZIL commit code and passed to metaslab_alloc(). Spreading
log blocks accross vdevs is important for performance: indeed, using
mutliple disks in parallel decreases the ZIL commit latency, which is
the main performance metric for synchronous writes. However, the current
implementation suffers from the following issues:
1) It would be best if the ZIL module was not aware of such low-level
details. They should be handled by the ZIO and metaslab modules;
2) Because the hint block pointer is managed per log, simultaneous
commits from multiple logs might use the same vdevs at the same time,
which is inefficient;
3) Because dmu_write() does not honor the block pointer hint, indirect
writes are not spread.
The naive solution of rotating the metaslab rotor each time a block is
allocated for the ZIL or dmu_sync() doesn't work in practice because the
first ZIL block to be written is actually allocated during the previous
commit. Consequently, when metaslab_alloc() decides the vdev for this
block, it will do so while a bunch of other allocations are happening at
the same time (from dmu_sync() and other ZILs). This means the vdev for
this block is chosen more or less at random. When the next commit
happens, there is a high chance (especially when the number of blocks
per commit is slightly less than the number of the disks) that one disk
will have to write two blocks (with a potential seek) while other disks
are sitting idle, which defeats spreading and increases the commit
latency.
This commit introduces a new concept in the metaslab allocator:
fastwrites. Basically, each top-level vdev maintains a counter
indicating the number of synchronous writes (from dmu_sync() and the
ZIL) which have been allocated but not yet completed. When the metaslab
is called with the FASTWRITE flag, it will choose the vdev with the
least amount of pending synchronous writes. If there are multiple vdevs
with the same value, the first matching vdev (starting from the rotor)
is used. Once metaslab_alloc() has decided which vdev the block is
allocated to, it updates the fastwrite counter for this vdev.
The rationale goes like this: when an allocation is done with
FASTWRITE, it "reserves" the vdev until the data is written. Until then,
all future allocations will naturally avoid this vdev, even after a full
rotation of the rotor. As a result, pending synchronous writes at a
given point in time will be nicely spread over all vdevs. This contrasts
with the previous algorithm, which is based on the implicit assumption
that blocks are written instantaneously after they're allocated.
metaslab_fastwrite_mark() and metaslab_fastwrite_unmark() are used to
manually increase or decrease fastwrite counters, respectively. They
should be used with caution, as there is no per-BP tracking of fastwrite
information, so leaks and "double-unmarks" are possible. There is,
however, an assert in the vdev teardown code which will fire if the
fastwrite counters are not zero when the pool is exported or the vdev
removed. Note that as stated above, marking is also done implictly by
metaslab_alloc().
ZIO also got a new FASTWRITE flag; when it is used, ZIO will pass it to
the metaslab when allocating (assuming ZIO does the allocation, which is
only true in the case of dmu_sync). This flag will also trigger an
unmark when zio_done() fires.
A side-effect of the new algorithm is that when a ZIL stops being used,
its last block can stay in the pending state (allocated but not yet
written) for a long time, polluting the fastwrite counters. To avoid
that, I've implemented a somewhat crude but working solution which
unmarks these pending blocks in zil_sync(), thus guaranteeing that
linguering fastwrites will get pruned at each sync event.
The best performance improvements are observed with pools using a large
number of top-level vdevs and heavy synchronous write workflows
(especially indirect writes and concurrent writes from multiple ZILs).
Real-life testing shows a 200% to 300% performance increase with
indirect writes and various commit sizes.
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #1013
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Differences between how paging is done on Solaris and Linux can cause
deadlocks if KM_SLEEP is used in any the following contexts.
* The txg_sync thread
* The zvol write/discard threads
* The zpl_putpage() VFS callback
This is because KM_SLEEP will allow for direct reclaim which may result
in the VM calling back in to the filesystem or block layer to write out
pages. If a lock is held over this operation the potential exists to
deadlock the system. To ensure forward progress all memory allocations
in these contexts must us KM_PUSHPAGE which disables performing any I/O
to accomplish the memory allocation.
Previously, this behavior was acheived by setting PF_MEMALLOC on the
thread. However, that resulted in unexpected side effects such as the
exhaustion of pages in ZONE_DMA. This approach touchs more of the zfs
code, but it is more consistent with the right way to handle these cases
under Linux.
This is patch lays the ground work for being able to safely revert the
following commits which used PF_MEMALLOC:
21ade34 Disable direct reclaim for z_wr_* threads
cfc9a5c Fix zpl_writepage() deadlock
eec8164 Fix ASSERTION(!dsl_pool_sync_context(tx->tx_pool))
Signed-off-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #726
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Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: Eric Schrock <[email protected]>
Reviewed by: Robert Mustacchi <[email protected]>
Reviewed by: Bill Pijewski <[email protected]>
Reviewed by: Richard Elling <[email protected]>
Reviewed by: Steve Gonczi <[email protected]>
Reviewed by: Garrett D'Amore <[email protected]>
Reviewed by: Dan McDonald <[email protected]>
Reviewed by: Albert Lee <[email protected]>
Approved by: Eric Schrock <[email protected]>
Refererces to Illumos issue:
https://www.illumos.org/issues/1909
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #680
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Today zfs tries to allocate blocks evenly across all devices.
This means when devices are imbalanced zfs will use lots of
CPU searching for space on devices which tend to be pretty
full. It should instead fail quickly on the full LUNs and
move onto devices which have more availability.
Reviewed by: Eric Schrock <[email protected]>
Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Albert Lee <[email protected]>
Reviewed by: Gordon Ross <[email protected]>
Approved by: Garrett D'Amore <[email protected]>
References to Illumos issue and patch:
- https://www.illumos.org/issues/510
- https://github.com/illumos/illumos-gate/commit/5ead3ed965
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #340
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If your only going to allow one allocator to be used and it is defined
at compile time there is no point including the others in the build.
This patch could/should be refined for Linux to make the metaslab
configurable at run time. That might be a bit tricky however since
you would need to quiese all IO. Short of that making it configurable
as a module load option would be a reasonable compromise.
Signed-off-by: Brian Behlendorf <[email protected]>
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Fix non-c90 compliant code, for the most part these changes
simply deal with where a particular variable is declared.
Under c90 it must alway be done at the very start of a block.
Signed-off-by: Brian Behlendorf <[email protected]>
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