Commit 86b3728141 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 <jens.axboe@oracle.com>
* '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 8bd1209cff)
cfq-iosched: reduce write depth only if sync was delayed
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 <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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 7667aa0630
Author: Vivek Goyal <vgoyal@redhat.com>
Date: Tue Dec 8 17:52:58 2009 -0500
cfq-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] <IRQ> [<ffffffff8103fab8>] __schedule_bug+0x5c/0x60
[ 3165.149821] [<ffffffff8103afd7>] ? __wake_up+0x44/0x4d
[ 3165.149821] [<ffffffff8153a979>] schedule+0xe3/0x7bc
[ 3165.149821] [<ffffffff8103a796>] ? cpumask_next+0x1d/0x1f
[ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [<ffffffff810422d8>] __cond_resched+0x2a/0x35
[ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [<ffffffff8153b1ee>] _cond_resched+0x2c/0x37
[ 3165.149821] [<ffffffff8100e2db>] is_valid_bugaddr+0x16/0x2f
[ 3165.149821] [<ffffffff811e4161>] report_bug+0x18/0xac
[ 3165.149821] [<ffffffff8100f1fc>] die+0x39/0x63
[ 3165.149821] [<ffffffff8153cde1>] do_trap+0x11a/0x129
[ 3165.149821] [<ffffffff8100d470>] do_invalid_op+0x96/0x9f
[ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [<ffffffff81034b4d>] ? enqueue_task+0x5c/0x67
[ 3165.149821] [<ffffffff8103ae83>] ? task_rq_unlock+0x11/0x13
[ 3165.149821] [<ffffffff81041aae>] ? try_to_wake_up+0x292/0x2a4
[ 3165.149821] [<ffffffff8100c935>] invalid_op+0x15/0x20
[ 3165.149821] [<ffffffffa000b21d>] ? cfq_dispatch_requests+0x6ba/0x93e
[cfq_iosched]
[ 3165.149821] [<ffffffff810df5a6>] ? virt_to_head_page+0xe/0x2f
[ 3165.149821] [<ffffffff811d8c2a>] blk_peek_request+0x191/0x1a7
[ 3165.149821] [<ffffffff811e5b8d>] ? kobject_get+0x1a/0x21
[ 3165.149821] [<ffffffff812c8d4c>] scsi_request_fn+0x82/0x3df
[ 3165.149821] [<ffffffff8110b2de>] ? bio_fs_destructor+0x15/0x17
[ 3165.149821] [<ffffffff810df5a6>] ? virt_to_head_page+0xe/0x2f
[ 3165.149821] [<ffffffff811d931f>] __blk_run_queue+0x42/0x71
[ 3165.149821] [<ffffffff811d9403>] blk_run_queue+0x26/0x3a
[ 3165.149821] [<ffffffff812c8761>] scsi_run_queue+0x2de/0x375
[ 3165.149821] [<ffffffff812b60ac>] ? put_device+0x17/0x19
[ 3165.149821] [<ffffffff812c92d7>] scsi_next_command+0x3b/0x4b
[ 3165.149821] [<ffffffff812c9b9f>] scsi_io_completion+0x1c9/0x3f5
[ 3165.149821] [<ffffffff812c3c36>] scsi_finish_command+0xb5/0xbe
I 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 <jmoyer@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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 <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
If there is a sequential reader running in a group, we wait for next request
to come in that group after slice expiry and once new request is in, we expire
the queue. Otherwise we delete the group from service tree and group looses
its fair share.
So far I was marking a queue as wait_busy if it had consumed its slice and
it was last queue in the group. But this condition did not cover following
two cases.
1.If a request completed and slice has not expired yet. Next request comes
in and is dispatched to disk. Now select_queue() hits and slice has expired.
This group will be deleted. Because request is still in the disk, this queue
will never get a chance to wait_busy.
2.If request completed and slice has not expired yet. Before next request
comes in (delay due to think time), select_queue() hits and expires the
queue hence group. This queue never got a chance to wait busy.
Gui was hitting the boundary condition 1 and not getting fairness numbers
proportional to weight.
This patch puts the checks for above two conditions and improves the fairness
numbers for sequential workload on rotational media. Check in select_queue()
takes care of case 1 and additional check in should_wait_busy() takes care
of case 2.
Reported-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
o Get rid of wait_busy_done flag. This flag only tells we were doing wait
busy on a queue and that queue got request so expire it. That information
can easily be obtained by (cfq_cfqq_wait_busy() && queue_is_not_empty). So
remove this flag and keep code simple.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
It doesn't make any sense to try to find out a close cooperating
queue if current cfqq is the only one in the group.
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
The introduction of ramp-up formula for async queue depths has
slowed down dirty page reclaim, by reducing async write performance.
This patch makes sure the formula kicks in only when sync request
was recently delayed.
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Fix a crash during boot reported by Jeff Moyer. Fix the issue of accessing
cfqq after freeing it.
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@carl.(none)>
After the merge of the IO controller patches, booting on my megaraid
box ran much slower. Vivek Goyal traced it down to megaraid discovery
creating tons of devices, each suffering a grace period when they later
kill that queue (if no device is found).
So lets use call_rcu() to batch these deferred frees, instead of taking
the grace period hit for each one.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
o Now issues of blkio controller and CFQ in module mode should be fixed.
Enable the cfq group scheduling support in module mode.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
o One of the goals of block IO controller is that it should be able to
support mulitple io control policies, some of which be operational at
higher level in storage hierarchy.
o To begin with, we had one io controlling policy implemented by CFQ, and
I hard coded the CFQ functions called by blkio. This created issues when
CFQ is compiled as module.
o This patch implements a basic dynamic io controlling policy registration
functionality in blkio. This is similar to elevator functionality where
ioschedulers register the functions dynamically.
o Now in future, when more IO controlling policies are implemented, these
can dynakically register with block IO controller.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
o blkio controller is inside the kernel and cfq makes use of interfaces
exported by blkio. CFQ can be a module too, hence export symbols used
by CFQ.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
With CLONE_IO, parent's io_context->nr_tasks is incremented, but never
decremented whenever copy_process() fails afterwards, which prevents
exit_io_context() from calling IO schedulers exit functions.
Give a task_struct to exit_io_context(), and call exit_io_context() instead of
put_io_context() in copy_process() cleanup path.
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
With CLONE_IO, copy_io() increments both ioc->refcount and ioc->nr_tasks.
However exit_io_context() only decrements ioc->refcount if ioc->nr_tasks
reaches 0.
Always call put_io_context() in exit_io_context().
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
cfq_arm_slice_timer() has logic to disable idle window for SSD device. The same
thing should be done at cfq_select_queue() too, otherwise we will still see
idle window. This makes the nonrot check logic consistent in cfq.
Tests in a intel SSD with low_latency knob close, below patch can triple disk
thoughput for muti-thread sequential read.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
o rq_noidle() is supposed to tell cfq that do not expect a request after this
one, hence don't idle. But this does not seem to work very well. For example
for direct random readers, rq_noidle = 1 but there is next request coming
after this. Not idling, leads to a group not getting its share even if
group_isolation=1.
o The right solution for this issue is to scan the higher layers and set
right flag (WRITE_SYNC or WRITE_ODIRECT). For the time being, this single
line fix helps. This should not have any significant impact when we are
not using cgroups. I will later figure out IO paths in higher layer and
fix it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
