01 Mar, 2010
6 commits
-
As the comment says the initial value of last_waited is never used, so
there is no need to initialise it with the current jiffies. Jiffies is
hot enough without accessing it for no reason.Signed-off-by: Richard Kennedy
Signed-off-by: Jens Axboe -
Reorder cfq_rb_root to remove 8 bytes of padding on 64 bit builds.
Consequently removing 56 bytes from cfq_group and 64 bytes from
cfq_data.Signed-off-by: Richard Kennedy
Signed-off-by: Jens Axboe -
Currently a queue can only dispatch up to 4 requests if there are other queues.
This isn't optimal, device can handle more requests, for example, AHCI can
handle 31 requests. I can understand the limit is for fairness, but we could
do a tweak: if the queue still has a lot of slice left, sounds we could
ignore the limit. Test shows this boost my workload (two thread randread of
a SSD) from 78m/s to 100m/s.
Thanks for suggestions from Corrado and Vivek for the patch.Signed-off-by: Shaohua Li
Signed-off-by: Jens Axboe -
Counters for requests "in flight" and "in driver" are used asymmetrically
in cfq_may_dispatch, and have slightly different meaning.
We split the rq_in_flight counter (was sync_flight) to count both sync
and async requests, in order to use this one, which is more accurate in
some corner cases.
The rq_in_driver counter is coalesced, since individual sync/async counts
are not used any more.Signed-off-by: Corrado Zoccolo
Signed-off-by: Jens Axboe -
CFQ currently applies the same logic of detecting seeky queues and
grouping them together for rotational disks as well as SSDs.
For SSDs, the time to complete a request doesn't depend on the
request location, but only on the size.
This patch therefore changes the criterion to group queues by
request size in case of SSDs, in order to achieve better fairness.Signed-off-by: Corrado Zoccolo
Signed-off-by: Jens Axboe -
Current seeky detection is based on average seek lenght.
This is suboptimal, since the average will not distinguish between:
* a process doing medium sized seeks
* a process doing some sequential requests interleaved with larger seeks
and even a medium seek can take lot of time, if the requested sector
happens to be behind the disk head in the rotation (50% probability).Therefore, we change the seeky queue detection to work as follows:
* each request can be classified as sequential if it is very close to
the current head position, i.e. it is likely in the disk cache (disks
usually read more data than requested, and put it in cache for
subsequent reads). Otherwise, the request is classified as seeky.
* an history window of the last 32 requests is kept, storing the
classification result.
* A queue is marked as seeky if more than 1/8 of the last 32 requests
were seeky.This patch fixes a regression reported by Yanmin, on mmap 64k random
reads.Reported-by: Yanmin Zhang
Signed-off-by: Corrado Zoccolo
Signed-off-by: Jens Axboe
26 Feb, 2010
6 commits
-
Except for SCSI no device drivers distinguish between physical and
hardware segment limits. Consolidate the two into a single segment
limit.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
The block layer calling convention is blk_queue_.
blk_queue_max_sectors predates this practice, leading to some confusion.
Rename the function to appropriately reflect that its intended use is to
set max_hw_sectors.Also introduce a temporary wrapper for backwards compability. This can
be removed after the merge window is closed.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
Add a BLK_ prefix to block layer constants.
Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
blk_queue_max_hw_sectors is no longer called by any subsystem and can be
removed.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
Clarify blk_queue_max_sectors and update documentation.
Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
There's no need to take css reference here, for the caller
has already called rcu_read_lock() to prevent cgroup from
being removed.Signed-off-by: Gui Jianfeng
Reviewed-by: Li Zefan
Acked-by: Vivek Goyal
Signed-off-by: Jens Axboe
25 Feb, 2010
1 commit
-
Conflicts:
include/linux/blkdev.hSigned-off-by: Jens Axboe
23 Feb, 2010
2 commits
-
Now that the bio list management stuff is generic, convert
generic_make_request to use bio lists instead of its own private bio
list implementation.Signed-off-by: Akinobu Mita
Cc: Christoph Hellwig
Signed-off-by: Jens Axboe -
This reverts commit fb1e75389bd06fd5987e9cda1b4e0305c782f854.
"Benjamin S." reports that the patch in question
causes a big drop in sequential throughput for him, dropping from
200MB/sec down to only 70MB/sec.Needs to be investigated more fully, for now lets just revert the
offending commit.Conflicts:
include/linux/blkdev.h
Signed-off-by: Jens Axboe
22 Feb, 2010
2 commits
-
This removes 8 bytes of padding from struct cfq_queue on 64 bit builds,
shrinking it's size to 256 bytes, so fitting into 1 fewer cachelines and
allowing 1 more object/slab in it's kmem_cache.Signed-off-by: Richard Kennedy
Reviewed-by: Jeff Moyer
----
patch against 2.6.33-rc8
tested on x86_64 AMDX2
Signed-off-by: Jens Axboe
05 Feb, 2010
1 commit
-
Currently we split seeky coop queues after 1s, which is too big. Below patch
marks seeky coop queue split_coop flag after one slice. After that, if new
requests come in, the queues will be splitted. Patch is suggested by Corrado.Signed-off-by: Shaohua Li
Reviewed-by: Corrado Zoccolo
Acked-by: Jeff Moyer
Signed-off-by: Jens Axboe
03 Feb, 2010
1 commit
-
Few weeks back, Shaohua Li had posted similar patch. I am reposting it
with more test results.This patch does two things.
- Do not idle on async queues.
- It also changes the write queue depth CFQ drives (cfq_may_dispatch()).
Currently, we seem to driving queue depth of 1 always for WRITES. This is
true even if there is only one write queue in the system and all the logic
of infinite queue depth in case of single busy queue as well as slowly
increasing queue depth based on last delayed sync request does not seem to
be kicking in at all.This patch will allow deeper WRITE queue depths (subjected to the other
WRITE queue depth contstraints like cfq_quantum and last delayed sync
request).Shaohua Li had reported getting more out of his SSD. For me, I have got
one Lun exported from an HP EVA and when pure buffered writes are on, I
can get more out of the system. Following are test results of pure
buffered writes (with end_fsync=1) with vanilla and patched kernel. These
results are average of 3 sets of run with increasing number of threads.AVERAGE[bufwfs][vanilla]
-------
job Set NR ReadBW(KB/s) MaxClat(us) WriteBW(KB/s) MaxClat(us)
--- --- -- ------------ ----------- ------------- -----------
bufwfs 3 1 0 0 95349 474141
bufwfs 3 2 0 0 100282 806926
bufwfs 3 4 0 0 109989 2.7301e+06
bufwfs 3 8 0 0 116642 3762231
bufwfs 3 16 0 0 118230 6902970AVERAGE[bufwfs] [patched kernel]
-------
bufwfs 3 1 0 0 270722 404352
bufwfs 3 2 0 0 206770 1.06552e+06
bufwfs 3 4 0 0 195277 1.62283e+06
bufwfs 3 8 0 0 260960 2.62979e+06
bufwfs 3 16 0 0 299260 1.70731e+06I also ran buffered writes along with some sequential reads and some
buffered reads going on in the system on a SATA disk because the potential
risk could be that we should not be driving queue depth higher in presence
of sync IO going to keep the max clat low.With some random and sequential reads going on in the system on one SATA
disk I did not see any significant increase in max clat. So it looks like
other WRITE queue depth control logic is doing its job. Here are the
results.AVERAGE[brr, bsr, bufw together] [vanilla]
-------
job Set NR ReadBW(KB/s) MaxClat(us) WriteBW(KB/s) MaxClat(us)
--- --- -- ------------ ----------- ------------- -----------
brr 3 1 850 546345 0 0
bsr 3 1 14650 729543 0 0
bufw 3 1 0 0 23908 8274517brr 3 2 981.333 579395 0 0
bsr 3 2 14149.7 1175689 0 0
bufw 3 2 0 0 21921 1.28108e+07brr 3 4 898.333 1.75527e+06 0 0
bsr 3 4 12230.7 1.40072e+06 0 0
bufw 3 4 0 0 19722.3 2.4901e+07brr 3 8 900 3160594 0 0
bsr 3 8 9282.33 1.91314e+06 0 0
bufw 3 8 0 0 18789.3 23890622AVERAGE[brr, bsr, bufw mixed] [patched kernel]
-------
job Set NR ReadBW(KB/s) MaxClat(us) WriteBW(KB/s) MaxClat(us)
--- --- -- ------------ ----------- ------------- -----------
brr 3 1 837 417973 0 0
bsr 3 1 14357.7 591275 0 0
bufw 3 1 0 0 24869.7 8910662brr 3 2 1038.33 543434 0 0
bsr 3 2 13351.3 1205858 0 0
bufw 3 2 0 0 18626.3 13280370brr 3 4 913 1.86861e+06 0 0
bsr 3 4 12652.3 1430974 0 0
bufw 3 4 0 0 15343.3 2.81305e+07brr 3 8 890 2.92695e+06 0 0
bsr 3 8 9635.33 1.90244e+06 0 0
bufw 3 8 0 0 17200.3 24424392So looks like it might make sense to include this patch.
Thanks
VivekSigned-off-by: Vivek Goyal
Signed-off-by: Jens Axboe
01 Feb, 2010
1 commit
-
I triggered a lockdep warning as following.
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.33-rc2 #1
-------------------------------------------------------
test_io_control/7357 is trying to acquire lock:
(blkio_list_lock){+.+...}, at: [] blkiocg_weight_write+0x82/0x9ebut task is already holding lock:
(&(&blkcg->lock)->rlock){......}, at: [] blkiocg_weight_write+0x3b/0x9ewhich lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&(&blkcg->lock)->rlock){......}:
[] validate_chain+0x8bc/0xb9c
[] __lock_acquire+0x723/0x789
[] lock_acquire+0x90/0xa7
[] _raw_spin_lock_irqsave+0x27/0x5a
[] blkiocg_add_blkio_group+0x1a/0x6d
[] cfq_get_queue+0x225/0x3de
[] cfq_set_request+0x217/0x42d
[] elv_set_request+0x17/0x26
[] get_request+0x203/0x2c5
[] get_request_wait+0x18/0x10e
[] __make_request+0x2ba/0x375
[] generic_make_request+0x28d/0x30f
[] submit_bio+0x8a/0x8f
[] submit_bh+0xf0/0x10f
[] ll_rw_block+0xc0/0xf9
[] ext3_find_entry+0x319/0x544 [ext3]
[] ext3_lookup+0x2c/0xb9 [ext3]
[] do_lookup+0xd3/0x172
[] link_path_walk+0x5fb/0x95c
[] path_walk+0x3c/0x81
[] do_path_lookup+0x21/0x8a
[] do_filp_open+0xf0/0x978
[] open_exec+0x1b/0xb7
[] do_execve+0xbb/0x266
[] sys_execve+0x24/0x4a
[] ptregs_execve+0x12/0x18-> #1 (&(&q->__queue_lock)->rlock){..-.-.}:
[] validate_chain+0x8bc/0xb9c
[] __lock_acquire+0x723/0x789
[] lock_acquire+0x90/0xa7
[] _raw_spin_lock_irqsave+0x27/0x5a
[] cfq_unlink_blkio_group+0x17/0x41
[] blkiocg_destroy+0x72/0xc7
[] cgroup_diput+0x4a/0xb2
[] dentry_iput+0x93/0xb7
[] d_kill+0x1c/0x36
[] dput+0xf5/0xfe
[] do_rmdir+0x95/0xbe
[] sys_rmdir+0x10/0x12
[] sysenter_do_call+0x12/0x32-> #0 (blkio_list_lock){+.+...}:
[] validate_chain+0x61c/0xb9c
[] __lock_acquire+0x723/0x789
[] lock_acquire+0x90/0xa7
[] _raw_spin_lock+0x1e/0x4e
[] blkiocg_weight_write+0x82/0x9e
[] cgroup_file_write+0xc6/0x1c0
[] vfs_write+0x8c/0x116
[] sys_write+0x3b/0x60
[] sysenter_do_call+0x12/0x32other info that might help us debug this:
1 lock held by test_io_control/7357:
#0: (&(&blkcg->lock)->rlock){......}, at: [] blkiocg_weight_write+0x3b/0x9e
stack backtrace:
Pid: 7357, comm: test_io_control Not tainted 2.6.33-rc2 #1
Call Trace:
[] print_circular_bug+0x91/0x9d
[] validate_chain+0x61c/0xb9c
[] __lock_acquire+0x723/0x789
[] lock_acquire+0x90/0xa7
[] ? blkiocg_weight_write+0x82/0x9e
[] _raw_spin_lock+0x1e/0x4e
[] ? blkiocg_weight_write+0x82/0x9e
[] blkiocg_weight_write+0x82/0x9e
[] cgroup_file_write+0xc6/0x1c0
[] ? trace_hardirqs_off+0xb/0xd
[] ? cpu_clock+0x2e/0x44
[] ? security_file_permission+0xf/0x11
[] ? rw_verify_area+0x8a/0xad
[] ? cgroup_file_write+0x0/0x1c0
[] vfs_write+0x8c/0x116
[] sys_write+0x3b/0x60
[] sysenter_do_call+0x12/0x32To prevent deadlock, we should take locks as following sequence:
blkio_list_lock -> queue_lock -> blkcg_lock.
The following patch should fix this bug.
Signed-off-by: Gui Jianfeng
Signed-off-by: Jens Axboe
29 Jan, 2010
1 commit
-
Updated 'nomerges' tunable to accept a value of '2' - indicating that _no_
merges at all are to be attempted (not even the simple one-hit cache).The following table illustrates the additional benefit - 5 minute runs of
a random I/O load were applied to a dozen devices on a 16-way x86_64 system.nomerges Throughput %System Improvement (tput / %sys)
-------- ------------ ----------- -------------------------
0 12.45 MB/sec 0.669365609
1 12.50 MB/sec 0.641519199 0.40% / 2.71%
2 12.52 MB/sec 0.639849750 0.56% / 2.96%Signed-off-by: Alan D. Brunelle
Signed-off-by: Jens Axboe
11 Jan, 2010
6 commits
-
In cfq_should_preempt(), we currently allow some cases where a non-RT request
can preempt an ongoing RT cfqq timeslice. This should not happen.
Examples include:o A sync_noidle wl type non-RT request pre-empting a sync_noidle wl type cfqq
on which we are idling.
o Once we have per-cgroup async queues, a non-RT sync request pre-empting a RT
async cfqq.Signed-off-by: Divyesh Shah
Signed-off-by: Jens Axboe -
All callers of the stacking functions use 512-byte sector units rather
than byte offsets. Simplify the code so the stacking functions take
sectors when specifying data offsets.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
It isn't used anymore, since AS was deleted.
Signed-off-by: Jens Axboe
-
DM does not want to know about partition offsets. Add a partition-aware
wrapper that DM can use when stacking block devices.Signed-off-by: Martin K. Petersen
Acked-by: Mike Snitzer
Reviewed-by: Alasdair G Kergon
Signed-off-by: Jens Axboe -
Discard alignment reporting for partitions was incorrect. Update to
match the algorithm used elsewhere.The alignment can be negative (misaligned). Fix format string
accordingly.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe -
The top device misalignment flag would not be set if the added bottom
device was already misaligned as opposed to causing a stacking failure.Also massage the reporting so that an error is only returned if adding
the bottom device caused the misalignment. I.e. don't return an error
if the top is already flagged as misaligned.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe
29 Dec, 2009
2 commits
-
Signed-off-by: OGAWA Hirofumi
Signed-off-by: Jens Axboe -
queue_sector_alignment_offset returned the wrong value which caused
partitions to report an incorrect alignment_offset. Since offset
alignment calculation is needed several places it has been split into a
separate helper function. The topology stacking function has been
updated accordingly.Furthermore, comments have been added to clarify how the stacking
function works.Signed-off-by: Martin K. Petersen
Tested-by: Mike Snitzer
Signed-off-by: Jens Axboe
28 Dec, 2009
1 commit
-
seek_mean could be very big sometimes, using it as close criteria is meaningless
as this doen't improve any performance. So if it's big, let's fallback to
default value.Reviewed-by: Corrado Zoccolo
Signed-off-by: Shaohua Li
Signed-off-by: Jens Axboe
21 Dec, 2009
1 commit
-
The stacking code incorrectly scaled up the data offset in some cases
causing misaligned devices to report alignment. Rewrite the stacking
algorithm to remedy this and apply the same alignment principles to the
discard handling.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe
18 Dec, 2009
3 commits
-
o CFQ now internally divides cfq queues in therr workload categories. sync-idle,
sync-noidle and async. Which workload to run depends primarily on rb_key
offset across three service trees. Which is a combination of mulitiple things
including what time queue got queued on the service tree.There is one exception though. That is if we switched the prio class, say
we served some RT tasks and again started serving BE class, then with-in
BE class we always started with sync-noidle workload irrespective of rb_key
offset in service trees.This can provide better latencies for sync-noidle workload in the presence
of RT tasks.o This patch gets rid of that exception and which workload to run with-in
class always depends on lowest rb_key across service trees. The reason
being that now we have multiple BE class groups and if we always switch
to sync-noidle workload with-in group, we can potentially starve a sync-idle
workload with-in group. Same is true for async workload which will be in
root group. Also the workload-switching with-in group will become very
unpredictable as it now depends whether some RT workload was running in
the system or not.Signed-off-by: Vivek Goyal
Reviewed-by: Gui Jianfeng
Acked-by: Corrado Zoccolo
Signed-off-by: Jens Axboe -
o Currently code does not seem to be using cfqd->nr_groups. Get rid of it.
Signed-off-by: Vivek Goyal
Reviewed-by: Gui Jianfeng
Signed-off-by: Jens Axboe -
o allow_merge() already checks if submitting task is pointing to same cfqq
as rq has been queued in. If everything is fine, we should not be having
a task in one cgroup and having a pointer to cfqq in other cgroup.Well I guess in some situations it can happen and that is, when a random
IO queue has been moved into root cgroup for group_isolation=0. In
this case, tasks's cgroup/group is different from where actually cfqq is,
but this is intentional and in this case merging should be allowed.The second situation is where due to close cooperator patches, multiple
processes can be sharing a cfqq. If everything implemented right, we should
not end up in a situation where tasks from different processes in different
groups are sharing the same cfqq as we allow merging of cooperating queues
only if they are in same group.Signed-off-by: Vivek Goyal
Reviewed-by: Gui Jianfeng
Signed-off-by: Jens Axboe
16 Dec, 2009
2 commits
-
Commit 86b37281411cf1e9bc0a6b5406c45edb7bd9ea5d adds a check for
misaligned stacking offsets, but it's buggy since the defaults are 0.
Hence all dm devices that pass in a non-zero starting offset will
be marked as misaligned amd dm will complain.A real fix is coming, in the mean time disable the discard granularity
check so that users don't worry about dm reporting about misaligned
devices.Signed-off-by: Jens Axboe
-
* 'for-2.6.33' of git://git.kernel.dk/linux-2.6-block:
cfq: set workload as expired if it doesn't have any slice left
Fix a CFQ crash in "for-2.6.33" branch of block tree
cfq: Remove wait_request flag when idle time is being deleted
cfq-iosched: commenting non-obvious initialization
cfq-iosched: Take care of corner cases of group losing share due to deletion
cfq-iosched: Get rid of cfqq wait_busy_done flag
cfq: Optimization for close cooperating queue searching
block,xd: Delay allocation of DMA buffers until device is known
drbd: Following the hmac change to SHASH (see linux commit 8bd1209cfff)
cfq-iosched: reduce write depth only if sync was delayed
15 Dec, 2009
1 commit
-
When a group is resumed, if it doesn't have workload slice left,
we should set workload_expires as expired. Otherwise, we might
start from where we left in previous group by error.
Thanks the idea from Corrado.Signed-off-by: Gui Jianfeng
Signed-off-by: Jens Axboe
11 Dec, 2009
1 commit
-
I think my previous patch introduced a bug which can lead to CFQ hitting
BUG_ON().The offending commit in for-2.6.33 branch is.
commit 7667aa0630407bc07dc38dcc79d29cc0a65553c1
Author: Vivek Goyal
Date: Tue Dec 8 17:52:58 2009 -0500cfq-iosched: Take care of corner cases of group losing share due to deletion
While doing some stress testing on my box, I enountered following.
login: [ 3165.148841] BUG: scheduling while
atomic: swapper/0/0x10000100
[ 3165.149821] Modules linked in: cfq_iosched dm_multipath qla2xxx igb
scsi_transport_fc dm_snapshot [last unloaded: scsi_wait_scan]
[ 3165.149821] Pid: 0, comm: swapper Not tainted
2.6.32-block-for-33-merged-new #3
[ 3165.149821] Call Trace:
[ 3165.149821] [] __schedule_bug+0x5c/0x60
[ 3165.149821] [] ? __wake_up+0x44/0x4d
[ 3165.149821] [] schedule+0xe3/0x7bc
[ 3165.149821] [] ? cpumask_next+0x1d/0x1f
[ 3165.149821] [] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [] __cond_resched+0x2a/0x35
[ 3165.149821] [] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [] _cond_resched+0x2c/0x37
[ 3165.149821] [] is_valid_bugaddr+0x16/0x2f
[ 3165.149821] [] report_bug+0x18/0xac
[ 3165.149821] [] die+0x39/0x63
[ 3165.149821] [] do_trap+0x11a/0x129
[ 3165.149821] [] do_invalid_op+0x96/0x9f
[ 3165.149821] [] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [] ? enqueue_task+0x5c/0x67
[ 3165.149821] [] ? task_rq_unlock+0x11/0x13
[ 3165.149821] [] ? try_to_wake_up+0x292/0x2a4
[ 3165.149821] [] invalid_op+0x15/0x20
[ 3165.149821] [] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [] ? virt_to_head_page+0xe/0x2f
[ 3165.149821] [] blk_peek_request+0x191/0x1a7
[ 3165.149821] [] ? kobject_get+0x1a/0x21
[ 3165.149821] [] scsi_request_fn+0x82/0x3df
[ 3165.149821] [] ? bio_fs_destructor+0x15/0x17
[ 3165.149821] [] ? virt_to_head_page+0xe/0x2f
[ 3165.149821] [] __blk_run_queue+0x42/0x71
[ 3165.149821] [] blk_run_queue+0x26/0x3a
[ 3165.149821] [] scsi_run_queue+0x2de/0x375
[ 3165.149821] [] ? put_device+0x17/0x19
[ 3165.149821] [] scsi_next_command+0x3b/0x4b
[ 3165.149821] [] scsi_io_completion+0x1c9/0x3f5
[ 3165.149821] [] scsi_finish_command+0xb5/0xbeI think I have hit following BUG_ON() in cfq_dispatch_request().
BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
Please find attached the patch to fix it. I have done some stress testing
with it and have not seen it happening again.o We should wait on a queue even after slice expiry only if it is empty. If
queue is not empty then continue to expire it.o If we decide to keep the queue then make cfqq=NULL. Otherwise select_queue()
will return a valid cfqq and cfq_dispatch_request() can hit following
BUG_ON().BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list))
Reviewed-by: Jeff Moyer
Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe
10 Dec, 2009
2 commits
-
Remove wait_request flag when idle time is being deleted, otherwise
it'll hit this path every time when a request is enqueued.Signed-off-by: Gui Jianfeng
Signed-off-by: Jens Axboe -
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (42 commits)
tree-wide: fix misspelling of "definition" in comments
reiserfs: fix misspelling of "journaled"
doc: Fix a typo in slub.txt.
inotify: remove superfluous return code check
hdlc: spelling fix in find_pvc() comment
doc: fix regulator docs cut-and-pasteism
mtd: Fix comment in Kconfig
doc: Fix IRQ chip docs
tree-wide: fix assorted typos all over the place
drivers/ata/libata-sff.c: comment spelling fixes
fix typos/grammos in Documentation/edac.txt
sysctl: add missing comments
fs/debugfs/inode.c: fix comment typos
sgivwfb: Make use of ARRAY_SIZE.
sky2: fix sky2_link_down copy/paste comment error
tree-wide: fix typos "couter" -> "counter"
tree-wide: fix typos "offest" -> "offset"
fix kerneldoc for set_irq_msi()
spidev: fix double "of of" in comment
comment typo fix: sybsystem -> subsystem
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