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286,663 commits

Author SHA1 Message Date
Johan Hedberg
14c0b60829 Bluetooth: Remove mgmt_set_service_cache
Instead of having an explicit service cache command we can make the mgmt
API simpler by implicitly enabling the cache when mgmt_read_info is
called for the first time and disabling it when mgmt_set_dev_class is
called.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:37:26 -02:00
Johan Hedberg
f7c6869ceb Bluetooth: Move mgmt_set_fast_connectable to the right location
Fast connectable is logically after the connectable property so that's
where it should show up in the code as well (it's also after connectable
in the settings bitfield).

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:34:48 -02:00
Johan Hedberg
69ab39ea5d Bluetooth: Update mgmt_read_info and related mgmt messages
This patch updates the mgmt_read_info and related messages to the latest
management API which uses a bitfield of settings instead of individual
boolean values.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:34:04 -02:00
Gustavo F. Padovan
590051de5c Bluetooth: Add ProFUSION's copyright
Add ProFUSION's copyright to some files I've been touching recently.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:59 -02:00
Gustavo F. Padovan
7f971041cf Bluetooth: Use system workqueue to schedule power_on
hdev->workqueue should be only for rx/tx, so move this one out.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:58 -02:00
Gustavo F. Padovan
6d438e335c Bluetooth: Remove work_add and work_del from hci_sysfs
As we run in process context now we don't need worqueue to add e del from
sysfs.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:58 -02:00
Gustavo F. Padovan
32845eb124 Bluetooth: Use new alloc_workqueue()
Update hdev workqueue API usage to use the new interface, this new
interface also allow us to mark this workqueue as WQ_HIGHPRI, so now rx
and tx work gets higher priority when running.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:58 -02:00
Gustavo F. Padovan
80b7ab3341 Bluetooth: move power_off to system workqueue
hdev->workqueue will be only for for rx/tx/cmd processing, all other small
works should go to the system workqueue for now.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:58 -02:00
Gustavo F. Padovan
3d57dc6806 Bluetooth: Change l2cap chan_list to use RCU
This list has much more reads than writes, so RCU makes senses here, also
it avoid deadlock against the socket lock.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:57 -02:00
Gustavo F. Padovan
03a0019481 Bluetooth: invert locking order in connect path
This move some checking code that was in l2cap_sock_connect() to
l2cap_chan_connect(). Thus we can invert the lock calls, i.e., call
lock_sock() before hci_dev_lock() to avoid a deadlock scenario.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:57 -02:00
Gustavo F. Padovan
f878fcad17 Bluetooth: convert info timer to delayed_work
Another step of remove interrupt context from Bluetooth Core.
Use the system workqueue.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:57 -02:00
Gustavo F. Padovan
3eff45eaf8 Bluetooth: convert tx_task to workqueue
This should simplify Bluetooth core processing a lot.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:57 -02:00
Gustavo F. Padovan
c347b765fe Bluetooth: Move command task to workqueue
As part of the moving on all the Bluetooth processing to Process context.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:57 -02:00
Gustavo F. Padovan
3c54711c4f Bluetooth: Don't disable tasklets to call hdev->notify()
It's pointless, we aren't protecting anything since btusb_notify()
schedules a work to run, then all it operation happens without protection.
If protection is really needed here, we will fix it further.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:57 -02:00
Gustavo F. Padovan
bf4c632524 Bluetooth: convert conn hash to RCU
Handling hci_conn_hash with RCU make us avoid some locking and disable
tasklets.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:56 -02:00
Gustavo F. Padovan
8192edef03 Bluetooth: Use RCU to manipulate chan_list
Instead of using tasklet_disable() to prevent acess to the channel use, we
can use RCU and improve the performance of our code.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:56 -02:00
Gustavo F. Padovan
d01b2ff4e6 Bluetooth: convert chan_lock to mutex
spin lock doesn't fit ok anymore on the new code based on workqueues.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:56 -02:00
Gustavo F. Padovan
67d0dfb5ec Bluetooth: move hci_task_lock to mutex
Now we can sleep in any path inside Bluetooth core, so mutex can make
sense here.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:56 -02:00
Gustavo F. Padovan
eb403a1b7e Bluetooth: Remove sk_backlog usage from L2CAP
We run everything in the same lock now. The backlog queue is useless now

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:55 -02:00
Gustavo F. Padovan
aa2ac881ba Bluetooth: Don't use spin_lock socket lock anymore
We now run everything in process context, so the mutex lock is the best
option. But in some places we still need the bh_lock_sock()

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:55 -02:00
Gustavo F. Padovan
721c41812d Bluetooth: Move L2CAP timers to workqueue
L2CAP timers also need to run in process context. As the works in l2cap
are small we are using the system worqueue.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:55 -02:00
Gustavo F. Padovan
b9cc553f12 Bluetooth: hci_conn_auto_accept() doesn't need locking
It doesn't really touch any sensitive information about hdev. So no need
to lock here.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:55 -02:00
Gustavo F. Padovan
db323f2fff Bluetooth: Use delayed work for advertisiment cache timeout
As HCI rx path is now done in process context it makes sense to do all the
timer in process context as well.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:55 -02:00
Gustavo F. Padovan
19c40e3bca Bluetooth: Use delayed_work for connection timeout
Bluetooth rx task runs now in a workqueue, so it a good approach run any
timer that share locking with process context code also in a workqueue.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:54 -02:00
Gustavo F. Padovan
09fd0de5bd Bluetooth: Replace spin_lock by mutex in hci_dev
Now we run everything in HCI in process context, so it's a better idea use
mutex instead spin_lock. The macro remains hci_dev_lock() (and I got rid
of hci_dev_lock_bh()), of course.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:54 -02:00
Marcel Holtmann
b78752cc71 Bluetooth: Process recv path in a workqueue instead of a tasklet
Run recv process in workqueue helps a lot with our processing as the recv
path will also be in the process context, i.e., now all our tx and rx are
in process context.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
2011-12-18 17:07:54 -02:00
Feng Tang
0d5fb5ea7d i2c-eg20t: correct the driver init order of pch_i2c_probe()
Before registering an adapter to i2c subsystem, we need make sure
driver is ready for incoming i2c xfer, becasue the i2c_add_adapter()
may trigger a i2c device driver's proble function which may start
some real i2c xfer. I met this issue when integrating a TSC2007 i2c
touch screen device with the i2c-eg20t driver.

This patch will call request_irq() and hw init before calling
i2c_add_adapter().

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2011-12-18 11:46:42 +00:00
Shubhrajyoti D
1d5a34fe99 I2C: OMAP: fix FIFO usage for OMAP4
Currently the fifo depth is set to zero for OMAP4 which disables
the FIFO usage. This patch enables the FIFO usage for I2C transactions
on OMAP4 also.

Tested on omap4430 and 3430.

Tested-and-Reported-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2011-12-18 11:45:54 +00:00
Tushar Behera
8ebe661dd2 i2c-s3c2410: Fix return code of s3c24xx_i2c_parse_dt_gpio
s3c24xx_i2c_parse_dt_gpio is called when cfg_gpio is not defined
in the platform data of the i2c device. When DT is not enabled,
the above function always returns -EINVAL. Since there can be
some i2c devices which don't need to configure any gpio lines,
the probe of such devices would fail here. Changing the default
return value to success would fix this issue.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2011-12-18 11:44:49 +00:00
Mark Brown
37de03ea12 i2c: i2c-s3c2410: Add a cpu_relax() to busy wait for bus idle
Be a bit more friendly.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
2011-12-18 11:44:26 +00:00
Jamie Iles
1b46f8782c ARM: picoxcell: implement watchdog restart
Allow the platform to be restarted by triggering the watchdog to expire
with the shortest possible expiry.  This should reset the CPU core and
all on-chip peripherals.

v2:	- use writel_relaxed().

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
2011-12-18 10:48:41 +00:00
Jamie Iles
a53bfa0736 MAINTAINERS: add maintainer entry for Picochip picoxcell
Add maintainer entry for the picoxcell machine support and associated
drivers.

v2:	- add 2-level pattern for drivers

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
2011-12-18 10:48:20 +00:00
Jamie Iles
8f37a0b496 ARM: picoxcell: move io mappings to common.c
Now that we have lost our machine specific ioremap() we just have one
mapping that covers all peripherals.  Move this to common.c to simplify
things a little.

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
2011-12-18 10:48:20 +00:00
Jamie Iles
98e27a5c13 ARM: picoxcell: don't reserve irq_descs
All irq_desc's are now dynamically allocated so we don't need to
statically reserve them.

v2:	- select SPARSE_IRQ and set .nr_irqs to NR_IRQS_LEGACY to skip
	ISA and IRQ 0.

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
2011-12-18 10:48:19 +00:00
Jamie Iles
513c4dd698 ARM: picoxcell: remove mach/memory.h
mach/memory.h is no longer required for simple platforms so remove it
for picoxcell.

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
2011-12-18 10:48:19 +00:00
Fernando Luis Vazquez Cao
b49d7d877f x86: Convert per-cpu counter icr_read_retry_count into a member of irq_stat
LAPIC related statistics are grouped inside the per-cpu
structure irq_stat, so there is no need for icr_read_retry_count
to be a standalone per-cpu variable.

This patch moves icr_read_retry_count to where it belongs.

Suggested-y: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Cc: Jörn Engel <joern@logfs.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 10:46:48 +01:00
Ingo Molnar
6e5ed27637 Merge commit 'v3.2-rc6' into x86/platform 2011-12-18 10:35:16 +01:00
Michael Demeter
d79a8869d8 x86/mrst: Add additional debug prints for pb_keys
Added additional debug output that we always seem to add
during power ons to validate firmware operation.

Signed-off-by: Michael Demeter <michael.demeter@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/20111215223116.10166.50803.stgit@bob.linux.org.uk
[ fixed line breaks, formatting and commit title. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 09:37:07 +01:00
Ingo Molnar
a228b5892b Merge branch 'mce-inject' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras into x86/mce 2011-12-18 09:18:45 +01:00
Alan Cox
933b9463a0 x86/intel config: Revamp configuration to allow for Moorestown and Medfield
This sets all up the other bits that need to be INTEL_MID
specific rather than Moorestown specific.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/20111217174318.7207.91543.stgit@bob.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 09:17:02 +01:00
Alan Cox
c95aaeffd8 x86/intel/scu/ipc: Match the changes in the x86 configuration
We need to depend on INTEL_MID because the SCU is Moorestown and
Medfield.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: mjg@redhat.com
Link: http://lkml.kernel.org/r/20111217174215.7096.7786.stgit@bob.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 09:16:07 +01:00
Jesper Juhl
1affc46cff x86: Use "do { } while(0)" for empty lock_cmos()/unlock_cmos() macros
gcc noticed (when using -Wempty-body) that our use of
lock_cmos() and unlock_cmos() in
arch/x86/include/asm/mach_traps.h is potentially problematic :

  arch/x86/include/asm/mach_traps.h:32:15: warning: suggest braces around empty body in an ¡else¢ statement [-Wempty-body]
  arch/x86/include/asm/mach_traps.h:40:16: warning: suggest braces around empty body in an ¡else¢ statement [-Wempty-body]

Let's just use the standard 'do {} while (0)' solution. That
shuts up gcc and also prevents future problems if the macros
should end up being used in a similar situation elsewhere.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1112180103130.21784@swampdragon.chaosbits.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 09:14:31 +01:00
Jesper Juhl
2ac13462b6 x86: Use "do { } while(0)" for empty flush_tlb_fix_spurious_fault() macro
If one builds the kernel with -Wempty-body one gets this
warning:

  mm/memory.c:3432:46: warning: suggest braces around empty body in an ¡if¢ statement [-Wempty-body]

due to the fact that 'flush_tlb_fix_spurious_fault' is a macro
that can sometimes be defined to nothing.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-mm@kvack.org
Cc: Michel Lespinasse <walken@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1112180128070.21784@swampdragon.chaosbits.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 09:14:18 +01:00
Alan Cox
a0c3832a57 x86/apb: Fix configuration constraints
The APB timer requires SFI, SCU and MID support

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/20111217215719.3743.93550.stgit@bob.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-12-18 09:09:47 +01:00
Wu Fengguang
bdaac4902a writeback: balanced_rate cannot exceed write bandwidth
Add an upper limit to balanced_rate according to the below inequality.
This filters out some rare but huge singular points, which at least
enables more readable gnuplot figures.

When there are N dd dirtiers,

	balanced_dirty_ratelimit = write_bw / N

So it holds that

	balanced_dirty_ratelimit <= write_bw

The singular points originate from dirty_rate in the below formular:

        balanced_dirty_ratelimit = task_ratelimit * write_bw / dirty_rate
where
	dirty_rate = (number of page dirties in the past 200ms) / 200ms

In the extreme case, if all dd tasks suddenly get blocked on something
else and hence no pages are dirtied at all, dirty_rate will be 0 and
balanced_dirty_ratelimit will be inf. This could happen in reality.

Note that these huge singular points are not a real threat, since they
are _guaranteed_ to be filtered out by the
	min(balanced_dirty_ratelimit, task_ratelimit)
line in bdi_update_dirty_ratelimit(). task_ratelimit is based on the
number of dirty pages, which will never _suddenly_ fly away like
balanced_dirty_ratelimit. So any weirdly large balanced_dirty_ratelimit
will be cut down to the level of task_ratelimit.

There won't be tiny singular points though, as long as the dirty pages
lie inside the dirty throttling region (above the freerun region).
Because there the dd tasks will be throttled by balanced_dirty_pages()
and won't be able to suddenly dirty much more pages than average.

Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:33 +08:00
Wu Fengguang
8279194054 writeback: do strict bdi dirty_exceeded
This helps to reduce dirty throttling polls and hence CPU overheads.

bdi->dirty_exceeded typically only helps when suddenly starting 100+
dd's on a disk, in which case the dd's may need to poll
balance_dirty_pages() earlier than tsk->nr_dirtied_pause.

CC: Jan Kara <jack@suse.cz>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:31 +08:00
Wu Fengguang
5b9b357435 writeback: avoid tiny dirty poll intervals
The LKP tests see big 56% regression for the case fio_mmap_randwrite_64k.
Shaohua manages to root cause it to be the much smaller dirty pause times
and hence much more frequent invocations to the IO-less balance_dirty_pages().
Since fio_mmap_randwrite_64k effectively contains both reads and writes,
the more frequent pauses triggered more idling in the cfq IO scheduler.

The solution is to increase pause time all the way up to the max 200ms
in this case, which is found to restore most performance. This will help
reduce CPU overheads in other cases, too.

Note that I don't expect many performance critical workloads to run this
access pattern: the mmap read-on-write is rather inefficient and could
be avoided by doing normal writes syscalls.

CC: Jan Kara <jack@suse.cz>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: Li Shaohua <shaohua.li@intel.com>
Tested-by: Li Shaohua <shaohua.li@intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:30 +08:00
Wu Fengguang
7ccb9ad536 writeback: max, min and target dirty pause time
Control the pause time and the call intervals to balance_dirty_pages()
with three parameters:

1) max_pause, limited by bdi_dirty and MAX_PAUSE

2) the target pause time, grows with the number of dd tasks
   and is normally limited by max_pause/2

3) the minimal pause, set to half the target pause
   and is used to skip short sleeps and accumulate them into bigger ones

The typical behaviors after patch:

- if ever task_ratelimit is far below dirty_ratelimit, the pause time
  will remain constant at max_pause and nr_dirtied_pause will be
  fluctuating with task_ratelimit

- in the normal cases, nr_dirtied_pause will remain stable (keep in the
  same pace with dirty_ratelimit) and the pause time will be fluctuating
  with task_ratelimit

In summary, someone has to fluctuate with task_ratelimit, because

	task_ratelimit = nr_dirtied_pause / pause

We normally prefer a stable nr_dirtied_pause, until reaching max_pause.

The notable behavior changes are:

- in stable workloads, there will no longer be sudden big trajectory
  switching of nr_dirtied_pause as concerned by Peter. It will be as
  smooth as dirty_ratelimit and changing proportionally with it (as
  always, assuming bdi bandwidth does not fluctuate across 2^N lines,
  otherwise nr_dirtied_pause will show up in 2+ parallel trajectories)

- in the rare cases when something keeps task_ratelimit far below
  dirty_ratelimit, the smoothness can no longer be retained and
  nr_dirtied_pause will be "dancing" with task_ratelimit. This fixes a
  (not that destructive but still not good) bug that
	  dirty_ratelimit gets brought down undesirably
	  <= balanced_dirty_ratelimit is under estimated
	  <= weakly executed task_ratelimit
	  <= pause goes too large and gets trimmed down to max_pause
	  <= nr_dirtied_pause (based on dirty_ratelimit) is set too large
	  <= dirty_ratelimit being much larger than task_ratelimit

- introduce min_pause to avoid small pause sleeps

- when pause is trimmed down to max_pause, try to compensate it at the
  next pause time

The "refactor" type of changes are:

The max_pause equation is slightly transformed to make it slightly more
efficient.

We now scale target_pause by (N * 10ms) on 2^N concurrent tasks, which
is effectively equal to the original scaling max_pause by (N * 20ms)
because the original code does implicit target_pause ~= max_pause / 2.
Based on the same implicit ratio, target_pause starts with 10ms on 1 dd.

CC: Jan Kara <jack@suse.cz>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:28 +08:00
Wu Fengguang
83712358ba writeback: dirty ratelimit - think time compensation
Compensate the task's think time when computing the final pause time,
so that ->dirty_ratelimit can be executed accurately.

        think time := time spend outside of balance_dirty_pages()

In the rare case that the task slept longer than the 200ms period time
(result in negative pause time), the sleep time will be compensated in
the following periods, too, if it's less than 1 second.

Accumulated errors are carefully avoided as long as the max pause area
is not hitted.

Pseudo code:

        period = pages_dirtied / task_ratelimit;
        think = jiffies - dirty_paused_when;
        pause = period - think;

1) normal case: period > think

        pause = period - think
        dirty_paused_when = jiffies + pause
        nr_dirtied = 0

                             period time
              |===============================>|
                  think time      pause time
              |===============>|==============>|
        ------|----------------|---------------|------------------------
        dirty_paused_when   jiffies

2) no pause case: period <= think

        don't pause; reduce future pause time by:
        dirty_paused_when += period
        nr_dirtied = 0

                           period time
              |===============================>|
                                  think time
              |===================================================>|
        ------|--------------------------------+-------------------|----
        dirty_paused_when                                       jiffies

Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:27 +08:00
Wu Fengguang
32c7f202a4 btrfs: fix dirtied pages accounting on sub-page writes
When doing 1KB sequential writes to the same page,
balance_dirty_pages_ratelimited_nr() should be called once instead of 4
times, the latter makes the dirtier tasks be throttled much too heavy.

Fix it with proper de-accounting on clear_page_dirty_for_io().

CC: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:25 +08:00