10 Dec, 2009
1 commit
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* '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
...
08 Dec, 2009
1 commit
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Fix a crash during boot reported by Jeff Moyer. Fix the issue of accessing
cfqq after freeing it.Reported-by: Jeff Moyer
Signed-off-by: Vivek Goyal
Reviewed-by: Jeff Moyer
Signed-off-by: Jens Axboe
07 Dec, 2009
1 commit
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Signed-off-by: Stephen Rothwell
Signed-off-by: Jens Axboe
06 Dec, 2009
1 commit
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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
04 Dec, 2009
30 commits
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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
Signed-off-by: Jens Axboe -
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
Signed-off-by: Jens Axboe -
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
Signed-off-by: Jens Axboe -
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
Signed-off-by: Jens Axboe -
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
Signed-off-by: Jens Axboe -
That is "success", "unknown", "through", "performance", "[re|un]mapping"
, "access", "default", "reasonable", "[con]currently", "temperature"
, "channel", "[un]used", "application", "example","hierarchy", "therefore"
, "[over|under]flow", "contiguous", "threshold", "enough" and others.Signed-off-by: André Goddard Rosa
Signed-off-by: Jiri Kosina -
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
Signed-off-by: Jens Axboe -
It's currently not an allowed configuration, so express that in Kconfig.
Signed-off-by: Jens Axboe
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They should not be declared inside some other file that's not related
to CFQ.Signed-off-by: Jens Axboe
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Signed-off-by: Jens Axboe
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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
Signed-off-by: Jens Axboe -
o If a group is running only a random reader, then it will not have enough
traffic to keep disk busy and we will reduce overall throughput. This
should result in better latencies for random reader though. If we don't
idle on random reader service tree, then this random reader will experience
large latencies if there are other groups present in system with sequential
readers running in these.o One solution suggested by corrado is that by default keep the random readers
or sync-noidle workload in root group so that during one dispatch round
we idle only once on sync-noidle tree. This means that all the sync-idle
workload queues will be in their respective group and we will see service
differentiation in those but not on sync-noidle workload.o Provide a tunable group_isolation. If set, this will make sure that even
sync-noidle queues go in their respective group and we wait on these. This
provides stronger isolation between groups but at the expense of throughput
if group does not have enough traffic to keep the disk busy.o By default group_isolation = 0
Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Async queues are not per group. Instead these are system wide and maintained
in root group. Hence their workload slice length should be calculated
based on total number of queues in the system and not just queues in the
root group.o As root group's default weight is 1000, make sure to charge async queue
more in terms of vtime so that it does not get more time on disk because
root group has higher weight.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o If a queue consumes its slice and then gets deleted from service tree, its
associated group will also get deleted from service tree if this was the
only queue in the group. That will make group loose its share.o For the queues on which we have idling on and if these have used their
slice, wait a bit for these queues to get backlogged again and then
expire these queues so that group does not loose its share.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Propagate blkio cgroup weight updation to associated cfq groups.
Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o If a task changes cgroup, drop reference to the cfqq associated with io
context and set cfqq pointer stored in ioc to NULL so that upon next request
arrival we will allocate a new queue in new group.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Do not allow following three operations across groups for isolation.
- selection of co-operating queues
- preemtpions across groups
- request merging across groups.o Async queues are currently global and not per group. Allow preemption of
an async queue if a sync queue in other group gets backlogged.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Export disk time and sector used by a group to user space through cgroup
interface.o Also export a "dequeue" interface to cgroup which keeps track of how many
a times a group was deleted from service tree. Helps in debugging.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Some debugging aids for CFQ.
Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o One can choose to change elevator or delete a cgroup. Implement group
reference counting so that both elevator exit and cgroup deletion can
take place gracefully.Signed-off-by: Vivek Goyal
Signed-off-by: Nauman Rafique
Signed-off-by: Jens Axboe -
o Determine the cgroup IO submitting task belongs to and create the cfq
group if it does not exist already.o Also link cfqq and associated cfq group.
o Currently all async IO is mapped to root group.
Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o This patch introduces the functionality to do the accounting of group time
when a queue expires. This time used decides which is the group to go
next.o Also introduce the functionlity to save and restore the workload type
context with-in group. It might happen that once we expire the cfq queue
and group, a different group will schedule in and we will lose the context
of the workload type. Hence save and restore it upon queue expiry.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o So far we had 300ms soft target latency system wide. Now with the
introduction of cfq groups, divide that latency by number of groups so
that one can come up with group target latency which will be helpful
in determining the workload slice with-in group and also the dynamic
slice length of the cfq queue.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Bring in the per cfq group weight and how vdisktime is calculated for the
group. Also bring in the functionality of updating the min_vdisktime of
the group service tree.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o This is basic implementation of blkio controller cgroup interface. This is
the common interface visible to user space and should be used by different
IO control policies as we implement those.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o So far we just had one cfq_group in cfq_data. To create space for more than
one cfq_group, we need to have a service tree of groups where all the groups
can be queued if they have active cfq queues backlogged in these.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Currently cfqq deletes a queue from service tree if it is empty (even if
we might idle on the queue). This patch keeps the queue on service tree
hence associated group remains on the service tree until we decide that
we are not going to idle on the queue and expire it.o This just helps in time accounting for queue/group and in implementation
of rest of the patches.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o Implement a macro to traverse each service tree in the group. This avoids
usage of double for loop and special condition for idle tree 4 times.o Macro is little twisted because of special handling of idle class service
tree.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o This patch introduce the notion of cfq groups. Soon we will can have multiple
groups of different weights in the system.o Various service trees (prioclass and workload type trees), will become per
cfq group. So hierarchy looks as follows.cfq_groups
|
workload type
|
cfq queueo When an scheduling decision has to be taken, first we select the cfq group
then workload with-in the group and then cfq queue with-in the workload
type.o This patch just makes various workload service tree per cfq group and
introduce the function to be able to choose a group for scheduling.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
o must_dispatch flag should be set only if we decided not to run the queue
and dispatch the request.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe
03 Dec, 2009
2 commits
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Since commit 2f5cb7381b737e24c8046fd4aeab571fb71315f5, each queue can send
up to 4 * 4 requests if only one queue exists. I wonder why we have such limit.
Device supports tag can send more requests. For example, AHCI can send 31
requests. Test (direct aio randread) shows the limits reduce about 4% disk
thoughput.
On the other hand, since we send one request one time, if other queue
pop when current is sending more than cfq_quantum requests, current queue will
stop send requests soon after one request, so sounds there is no big latency.Signed-off-by: Shaohua Li
Signed-off-by: Jens Axboe -
The discard ioctl is used by mkfs utilities to clear a block device
prior to putting metadata down. However, not all devices return zeroed
blocks after a discard. Some drives return stale data, potentially
containing old superblocks. It is therefore important to know whether
discarded blocks are properly zeroed.Both ATA and SCSI drives have configuration bits that indicate whether
zeroes are returned after a discard operation. Implement a block level
interface that allows this information to be bubbled up the stack and
queried via a new block device ioctl.Signed-off-by: Martin K. Petersen
Signed-off-by: Jens Axboe
30 Nov, 2009
1 commit
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This reverts commit 3586e917f2c7df769d173c4ec99554cb40a911e5.
Corrado Zoccolo correctly points out, that we need
consistency of rb_key offset across groups. This means we cannot properly
use the per-service_tree service count. Revert this change.Signed-off-by: Jens Axboe
26 Nov, 2009
3 commits
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Idling logic was disabled in some corner cases, leading to unfair share
for noidle queues.
* the idle timer was not armed if there were other requests in the
driver. unfortunately, those requests could come from other workloads,
or queues for which we don't enable idling. So we will check only
pending requests from the active queue
* rq_noidle check on no-idle queue could disable the end of tree idle if
the last completed request was rq_noidle. Now, we will disable that
idle only if all the queues served in the no-idle tree had rq_noidle
requests.Reported-by: Vivek Goyal
Signed-off-by: Corrado Zoccolo
Acked-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Seeky sync queues with large depth can gain unfairly big share of disk
time, at the expense of other seeky queues. This patch ensures that
idling will be enabled for queues with I/O depth at least 4, and small
think time. The decision to enable idling is sticky, until an idle
window times out without seeing a new request.The reasoning behind the decision is that, if an application is using
large I/O depth, it is already optimized to make full utilization of
the hardware, and therefore we reserve a slice of exclusive use for it.Reported-by: Vivek Goyal
Signed-off-by: Corrado Zoccolo
Signed-off-by: Jens Axboe -
An incoming no-idle queue should preempt the active no-idle queue
only if the active queue is idling due to service tree empty.
Previous code was buggy in two ways:
* it relied on service_tree field to be set on the active queue, while
it is not set when the code is idling for a new request
* it didn't check for the service tree empty condition, so could lead to
LIFO behaviour if multiple queues with depth > 1 were preempting each
other on an non-NCQ device.Reported-by: Vivek Goyal
Signed-off-by: Corrado Zoccolo
Acked-by: Vivek Goyal
Signed-off-by: Jens Axboe
