When the number of processes performing I/O concurrently increases,
a fixed time slice per process will cause large latencies.

This patch, if low_latency mode is enabled,  will scale the time slice
assigned to each process according to a 300ms target latency.

In order to keep fairness among processes:
* The number of active processes is computed using a special form of
running average, that quickly follows sudden increases (to keep latency low),
and decrease slowly (to have fairness in spite of rapid decreases of this
value).

To safeguard sequential bandwidth, we impose a minimum time slice
(computed using 2*cfq_slice_idle as base, adjusted according to priority
and async-ness).
Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

If active queue hasn't enough requests and idle window opens, cfq will not
dispatch sufficient requests to hardware. In such situation, current code
will zero hw_tag. But this is because cfq doesn't dispatch enough requests
instead of hardware queue doesn't work. Don't zero hw_tag in such case.
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

cfq_queues are merged if they are issuing requests within the mean seek
distance of one another.  This patch detects when the coopearting stops and
breaks the queues back up.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The flag used to indicate that a cfqq was allowed to jump ahead in the
scheduling order due to submitting a request close to the queue that
just executed.  Since closely cooperating queues are now merged, the flag
holds little meaning.  Change it to indicate that multiple queues were
merged.  This will later be used to allow the breaking up of merged queues
when they are no longer cooperating.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

When cooperating cfq_queues are detected currently, they are allowed to
skip ahead in the scheduling order.  It is much more efficient to
automatically share the cfq_queue data structure between cooperating processes.
Performance of the read-test2 benchmark (which is written to emulate the
dump(8) utility) went from 12MB/s to 90MB/s on my SATA disk.  NFS servers
with multiple nfsd threads also saw performance increases.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

async cfq_queue's are already shared between processes within the same
priority, and forthcoming patches will change the mapping of cic to sync
cfq_queue from 1:1 to 1:N.  So, calculate the seekiness of a process
based on the cfq_queue instead of the cfq_io_context.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Add cciss_allow_hpsa module parameter.  This parameter causes
the cciss driver to ignore any Smart Array devices known to be
supported by the hpsa driver.
Signed-off-by: NStephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Fix multiple calls to pci_release_regions.  If cciss_pci_init
fails, it already does any necessary call to pci_release_regions,
so this does not need to be done again in cciss_init_one in that
case.
Signed-off-by: NStephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Fix kernel-doc notation in blk-settings.c::blk_queue_max_discard_sectors().
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The space is not script friendly, kill it.
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

It makes sense to do IOWAIT when someone is blocked
due to IO throttle, as suggested by Kame and Peter.

There is an old comment for not doing IOWAIT on throttle,
however it has been mismatching the code for a long time.

If we stop accounting IOWAIT for 2.6.32, it could be an
undesirable behavior change. So restore the io_schedule.

CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

elv_iosched_store() ignore the return value of strstrip().  It makes small
inconsistent behavior.

This patch fixes it.

 <before>
 ====================================
 # cd /sys/block/{blockdev}/queue

 case1:
 # echo "anticipatory" > scheduler
 # cat scheduler
 noop [anticipatory] deadline cfq

 case2:
 # echo "anticipatory " > scheduler
 # cat scheduler
 noop [anticipatory] deadline cfq

 case3:
 # echo " anticipatory" > scheduler
 bash: echo: write error: Invalid argument

 <after>
 ====================================
 # cd /sys/block/{blockdev}/queue

 case1:
 # echo "anticipatory" > scheduler
 # cat scheduler
 noop [anticipatory] deadline cfq

 case2:
 # echo "anticipatory " > scheduler
 # cat scheduler
 noop [anticipatory] deadline cfq

 case3:
 # echo " anticipatory" > scheduler
 noop [anticipatory] deadline cfq

Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

If the average think time is larger than the remaining time slice
for any given queue, don't allow it to idle. A succesful idle also
means that we need to dispatch and complete a request, so if we don't
even have time left for the idle process, we would overrun the slice
in any case.
Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Saves 16 bytes of text, woohoo. But the more important point is
that it makes the code more readable when returning bool for 0/1
cases.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

CFQ enables idle only for processes that think less than the allowed
idle time. Since idle time is lower for seeky queues, we should use the
correct value in the comparison.
Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

drbd_int.h uses __ratelimit(), so it needs to #include ratelimit.h:

drivers/block/drbd/drbd_int.h:1765: error: implicit declaration of function '__ratelimit'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: drbd-dev@lists.linbit.com
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

We should subtract the slice residual from the rb tree key, since
a negative residual count indicates that the cfqq overran its slice
the last time. Hence we want to add the overrun time, to position
it a bit further away in the service tree.
Reported-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Makes the whole thing easier to read, cfq_dispatch_requests() was
a bit messy before.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Makes it easier to read than the 0.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Commit a9327cac added seperate read
and write statistics of in_flight requests. And exported the number
of read and write requests in progress seperately through sysfs.

But  Corrado Zoccolo <czoccolo@gmail.com> reported getting strange
output from "iostat -kx 2". Global values for service time and
utilization were garbage. For interval values, utilization was always
100%, and service time is higher than normal.

So this was reverted by commit 0f78ab98

The problem was in part_round_stats_single(), I missed the following:
        if (now == part->stamp)
                return;

-       if (part->in_flight) {
+       if (part_in_flight(part)) {
                __part_stat_add(cpu, part, time_in_queue,
                                part_in_flight(part) * (now - part->stamp));
                __part_stat_add(cpu, part, io_ticks, (now - part->stamp));

With this chunk included, the reported regression gets fixed.
Signed-off-by: NNikanth Karthikesan <knikanth@suse.de>

--
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Now we have the capabilities of the sending process available,
use them to enforce CAP_SYS_ADMIN.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

It was briefly introduced to allow CFQ to to delayed scheduling,
but we ended up removing that feature again. So lets kill the
function and export, and just switch CFQ back to the normal work
schedule since it is now passing in a '0' delay from all call
sites.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The RR service tree is indexed by a key that is relative to current jiffies.
This can cause problems on jiffies wraparound.

The patch fixes it using time_before comparison, and changing
the add_front path to use a relative number, too.
Signed-off-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

cfq uses rq->start_time as the fifo indicator, but that field may
get modified prior to cfq doing it's fifo list adjustment when
a request gets merged with another request. This can cause the
fifo list to become unordered.
Reported-by: NCorrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

I'm skipping -rc2 because the -rc1 Makefile mistakenly said -rc2, so in
order to avoid confusion, I'm jumping from -rc1 to -rc3.  That way, when
'uname' (or an oops report) says 2.6.32-rc2, there's no confusion about
whether people perhaps meant -rc1 or -rc2.

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'acpi-pad' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6:
  acpi_pad: build only on X86
  ACPI: create Processor Aggregator Device driver

Fixup trivial conflicts in MAINTAINERS file.

* 'sfi-release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-sfi-2.6:
  SFI: remove __init from sfi_verify_table
  SFI: fix section mismatch warnings in sfi_core.c

* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6:
  ACPI: EC: Don't parse DSDT for EC early init on Compal
  ACPI: EC: Rewrite DMI checks
  ACPI: dock: fix "sibiling" typo
  ACPI: kill overly verbose "throttling states" log messages
  ACPI: Fix bound checks for copy_from_user in the acpi /proc code
  ACPI: fix bus scanning memory leaks
  ACPI: EC: Restart command even if no interrupts from EC
  sony-laptop: Don't unregister the SPIC driver if it wasn't registered
  sony-laptop: remove _INI call at init time
  sony-laptop: SPIC unset IRQF_SHARED, set IRQF_DISABLED
  sony-laptop: remove device_ctrl and the SPIC mini drivers

* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  macintosh: Don't assume i2c device probing always succeeds
  i2c: Hide probe errors caused by ACPI resource conflicts
  i2c: Minor documentation update
  mfd: AB3100 drop unused module parameters
  Staging: IIO: tsl2561: Drop unused module parameters
  leds: leds-pca9532 - Drop unused module parameters
  ltc4215/ltc4245: Discard obsolete detect methods
  ds2482: Discard obsolete detect method
  max6875: Discard obsolete detect method
  i2c: Move misc devices documentation

If i2c device probing fails, then there is no driver to dereference
after calling i2c_new_device(). Stop assuming that probing will always
succeed, to avoid NULL pointer dereferences. We have an easier access
to the driver anyway.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Tested-by: NTim Shepard <shep@alum.mit.edu>
Cc: Colin Leroy <colin@colino.net>

When an ACPI resource conflict is detected, error messages are already
printed by ACPI. There's no point in causing the driver core to print
more error messages, so return one of the error codes for which no
message is printed.

This fixes bug #14293:
http://bugzilla.kernel.org/show_bug.cgi?id=14293Signed-off-by: NJean Delvare <khali@linux-fr.org>

The sysfs path to i2c adapters has changed recently, update the
documentation to reflect that change.
Signed-off-by: NJean Delvare <khali@linux-fr.org>

The I2C_CLIENT_INSMOD_1 macro is only useful for i2c drivers which
implement device detection. The ab3100 driver doesn't, so there is no
point in calling it.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Acked-by: NLinus Walleij <linus.walleij@stericsson.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>

The I2C_CLIENT_INSMOD macro is only useful for i2c drivers which
implement device detection. The tsl2561 driver doesn't, so there
is no point in calling it.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Jonathan Cameron <jic23@cam.ac.uk>

The I2C_CLIENT_INSMOD_1 macro is only useful for i2c drivers which
implement device detection. The leds-pca9532 driver doesn't, so there
is no point in calling it.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Riku Voipio <riku.voipio@iki.fi>

There is no point in implementing a detect callback for the LTC4215
and LTC4245, as these devices can't be detected. It was there solely
to handle "force" module parameters to instantiate devices, but now
we have a better sysfs interface that can do the same.

So we can get rid of the ugly module parameters and the detect
callbacks. This shrinks the binary module sizes by 36% and 46%,
respectively.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Ira W. Snyder <iws@ovro.caltech.edu>