Revert "block: row: Increase idling time"

This reverts commit fcf4abcf115c937df7e48e6ae13360f49a9a4d34.
Revert "block: row: hardcode magic values"

This reverts commit d6bcbfe60adc61dbdd43ae71feeef73b0f3d93dc.
block: row: Dispatch requests according to their io-priority

This patch implements "application-hints" which is a way the issuing
application can notify the scheduler on the priority of its request.
This is done by setting the io-priority of the request.
This patch reuses an already existing mechanism of io-priorities developed
for CFQ. Please refer to kernel/Documentation/block/ioprio.txt for
usage example and explanations.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Idling mechanism re-factoring

At the moment idling in ROW is implemented by delayed work that uses
jiffies granularity which is not very accurate. This patch replaces
current idling mechanism implementation with hrtime API, which gives
nanosecond resolution (instead of jiffies).

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Don't notify URGENT if there are un-completed urgent req

When ROW scheduler reports to the block layer that there is an urgent
request pending, the device driver may decide to stop the transmission
of the current request in order to handle the urgent one. If the current
transmitted request is an urgent request - we don't want it to be
stopped.
Due to the above ROW scheduler won't notify of an urgent request if
there are urgent requests in flight.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Update initial values of ROW data structures

This patch sets the initial values of internal ROW
parameters.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
[smuckle@codeaurora.org: ported from msm-3.7]
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
block: row: Re-design urgent request notification mechanism

When ROW scheduler reports to the block layer that there is an urgent
request pending, the device driver may decide to stop the transmission
of the current request in order to handle the urgent one. This is done
in order to reduce the latency of an urgent request. For example:
long WRITE may be stopped to handle an urgent READ.

This patch updates the ROW URGENT notification policy to apply with the
below:

- Don't notify URGENT if there is an un-completed URGENT request in driver
- After notifying that URGENT request is present, the next request
  dispatched is the URGENT one.
- At every given moment only 1 request can be marked as URGENT.
  Independent of it's location (driver or scheduler)

Other changes to URGENT policy:
- Only READ queues are allowed to notify of an URGENT request pending.

CR fix:
If a pending urgent request (A) gets merged with another request (B)
A is removed from scheduler queue but is not removed from
rd->pending_urgent_rq.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: blk-core: add printk_ratelimit

On failure of requests the console is flooded with prints,
which result in a watchdog bark.
This patch limits the number of prints to console thus, avoiding
the bark.

Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
block: row: Prevent starvation of regular priority by high priority

At the moment all REGULAR and LOW priority requests are starved as long as
there are HIGH priority requests to dispatch.
This patch prevents the above starvation by setting a starvation limit the
REGULAR\LOW priority requests can tolerate.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Update sysfs functions

All ROW (time related) configurable parameters are stored in ms so there
is no need to convert from/to ms when reading/updating them via sysfs.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Fix starvation tolerance values

The current starvation tolerance values increase the boot time
since high priority SW requests are delayed by regular priority requests.
In order to overcome this, increase the starvation tolerance values.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
block: urgent: Fix dispatching of URGENT mechanism

There are cases when blk_peek_request is called not from blk_fetch_request
thus the URGENT request may be started but the flag q->dispatched_urgent is
not updated.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: drop @tsk from attempt_plug_merge() and explain sync rules

attempt_plug_merge() accesses elevator without holding queue_lock and
may call into ->elevator_bio_merge_fn().  The elvator is guaranteed to
be valid because it's accessed iff the plugged list has requests and
elevator is never exited with live requests, so as long as the
elevator method can deal with unlocked access, this is safe.

Explain the sync rules around attempt_plug_merge() and drop the
unnecessary @tsk parameter.

This patch doesn't introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
block: row: Fix forward ported functionalities
block: row: hardcode magic values.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
block: Remove "requeuing urgent req" error messages

It is possible for URGENT request to be requeued/reinserted if it was
fetched during the creation of a packed list. This end case is rare and is
not handled at the moment.
This patch changes the messages notifying of the above to debug level
(instead of error) in order to clear the dmesg log.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
hrtimer:__run_hrtimer races with enqueue_hrtimer

We hit a kernel panic at __run_hrtimer=>BUG_ON(timer->state != HRTIMER_STATE_CALLBACK).
<2>[   10.226053, 3] kernel BUG at /home/android/xiaobing/ymz/r4/hardware/intel/linux-2.6/kernel/hrtimer.c:1228!
<0>[   10.235682, 3] invalid opcode: 0000 [#1] PREEMPT SMP
<4>[   10.240716, 3] Modules linked in: wl12xx_sdio wl12xx mac80211 cfg80211 compat btwilink rmi4(C) fmdrv_chr st_drv matrix(C)
<4>[   10.251651, 3]
<4>[   10.253391, 3] Pid: 68, comm: kworker/3:4 Tainted: G        WC  3.0.34-140430-g2af538d #45 Intel Corporation CloverTrail/FFRD
<4>[   10.264674, 3] EIP: 0060:[<c126c7ed>] EFLAGS: 00010002 CPU: 3
<4>[   10.270411, 3] EIP is at __run_hrtimer+0xbd/0x240
<4>[   10.275091, 3] EAX: 00000001 EBX: f67fb6b8 ECX: f57b4000 EDX: 00007301
<4>[   10.281602, 3] ESI: c1d614c0 EDI: f67fb680 EBP: f57b5dd8 ESP: f57b5da8
<4>[   10.288113, 3]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
<0>[   10.293754, 3] Process kworker/3:4 (pid: 68, ti=f57b4000 task=f57aa730 task.ti=f57b4000)
<0>[   10.301827, 3] Stack:
<4>[   10.304083, 3]  00000000 c1afef40 f57b5dd8 c167a6e0 f67fb680 20b366e3 f67fb6b8 f57b5e14
<4>[   10.312069, 3]  00000001 f67fb6b8 00000001 f67fb680 f57b5e28 c126d1e5 f57b5e08 c126f325
<4>[   10.320055, 3]  00000000 86b9868d 00000001 86b9868d 00000001 00000003 ffffffff 7fffffff
<0>[   10.328041, 3] Call Trace:
<4>[   10.330742, 3]  [<c167a6e0>] ? gburst_thread_stop.isra.25+0x40/0x40
<4>[   10.336988, 3]  [<c126d1e5>] hrtimer_interrupt+0xd5/0x250
<4>[   10.342368, 3]  [<c126f325>] ? sched_clock_cpu+0xe5/0x150
<4>[   10.347753, 3]  [<c1871d44>] smp_apic_timer_interrupt+0x54/0x88
<4>[   10.353654, 3]  [<c1496558>] ? trace_hardirqs_off_thunk+0xc/0x14
<4>[   10.359643, 3]  [<c186be9f>] apic_timer_interrupt+0x2f/0x34
<4>[   10.365199, 3]  [<c186e60f>] ? sub_preempt_count+0x1f/0x50
<4>[   10.370669, 3]  [<c149558a>] delay_tsc+0x3a/0xc0
<6>[   10.371589, 0] android_work: did not send uevent (0 0   (null))
<4>[   10.381171, 3]  [<c14954e3>] __const_udelay+0x23/0x30
<4>[   10.386207, 3]  [<c16d043a>] mdfld_dsi_send_dcs+0x12a/0x5d0
<4>[   10.391760, 3]  [<c186b6c6>] ? _raw_spin_unlock_irqrestore+0x26/0x50
<4>[   10.398101, 3]  [<c16af431>] ? ospm_power_using_hw_begin+0xa1/0x350
<4>[   10.399053, 3]  [<c186a49f>] ? __mutex_lock_slowpath+0x1ff/0x2f0
<4>[   10.399069, 3]  [<c16bd59e>] mdfld_dbi_update_panel+0x21e/0x2d0
<4>[   10.399085, 3]  [<c16b1ae1>] mdfld_te_handler_work+0x71/0x80
<4>[   10.399099, 3]  [<c12642be>] process_one_work+0xfe/0x3f0
<4>[   10.399114, 3]  [<c16b1a70>] ? mdfld_async_flip_te_handler+0xf0/0xf0

Basically, __run_hrtimer has a race with enqueue_hrtimer. When __run_hrtimer calls
the timer callback fn, another thread might call enqueue_hrtimer or hrtimer_start
to requeue it, and the timer->state is equal to HRTIMER_STATE_CALLBACK|HRTIMER_STATE_ENQUEUED,
which causes the BUG_ON(timer->state != HRTIMER_STATE_CALLBACK) checking fails.

The patch fixes it by checking only bit HRTIMER_STATE_CALLBACK.

Signed-off-by: Yanmin Zhang <yanmin.zhang@intel.com>
Reviewed-by: He, Bo <bo.he@intel.com>