omap: mailbox: enable mailbox irq per instance

The machine-specific omap2_mbox_startup is called only once
to initialize the whole mbox module. Enabling mbox irq at
startup is only enabling the irq of the very first mailbox
instance created.

The enable_irq function should be called every time a
new mbox instance is created, in the generic platform
mailbox layer.

Change-Id: I1b7148fd0342a335e3b45cfe349c43a8491ae5c1
Signed-off-by: Juan Gutierrez <jgutierrez@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
omap: mailbox: add pm constraint field to mbox structure

By adding this field, the pm qos apis can be selectively applied
only if the pm constraint is set to a +ve value.

Change-Id: I3b6930e85f65f7354826813798dec76b25149370
Signed-off-by: Subramaniam C.A <subramaniam.ca@ti.com>
Signed-off-by: Omar Ramirez Luna <omar.ramirez@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
omap: mailbox: relax constraint to allow powerdomain to go to CSWR

The mailbox registers can be accessed and configured by other remote
processor initiators, and hence the driver has to be responsible for
maintaining the register context when they are active. This is
achieved by the mailbox driver by requesting a latency constraint
on the power domain that it belongs to.

The current constraint value (10) is high and restricts the power
domain to remain in ON state as long as a remote processor is
active. This value is relaxed to 400 to allow a lower power CSWR
state that can still retain the context during cpuidle path and
a remote processor is active.

The constraint is completely removed when the remote processor is
suspended. The mailbox context is saved and restored properly
when suspending the remote processor.

Change-Id: I152b57e982dc8e5739808cbbbe8bd5cc96223ffa
Signed-off-by: Miguel Vadillo <vadillo@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
omap: iommu: apply latency constraint based on power domain

When the iommu is taken out of reset, a latency constraint is
set to avoid its power domain going to retention/off. The iommus
for DSP and M3 reside in DSP and Core power domains respectively,
and therefore the API for setting the constraints is different.
This patch uses the appropriate API depending on the iommu (power
domain) the latency constraint is being applied on.

Change-Id: I3fa4485b3c405aa10c32a3fe0b7ac694d484ee21
Signed-off-by: Juan Gutierrez <jgutierrez@ti.com>
Signed-off-by: Subramaniam C.A <subramaniam.ca@ti.com>
omap: iommu: program constraints based on platform data

IOMMU driver requests and releases constraints in iommu_get
and iommu_put respectively. These constraints are actually
needed only on OMAP4 and beyond for sub-systems that have
an AMMU. The current driver code has these values hard-coded
for all the chips.

A new platform data field has been added now for the constraints
values, and this allows the values to be programmed based on
the OMAP chip and also allow a unique value if needed for each
iommu instance.

The logic in IOMMU driver code is adjusted to request the
constraints only if the relevant platform data field is set.

Change-Id: Iab18cbdde1d7fa7507dbff0b9512c8577b42fefd
Signed-off-by: Subramaniam C.A <subramaniam.ca@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
omap: iommu: relax constraint value to allow CSWR

The iommu driver currently requests a latency constraint,
if configured in platform data, on the power domain it is
present in. These values are required only for OMAP4 and
beyond and is done to ensure the AMMU context is maintained
when the corresponding power domain goes to a low power state
during cpuidle path. The AMMU context is retained in CSWR, but
is lost in OSWR.

The current constraint value (10) for OMAP4+ is high and
restricts the power domain to remain in ON state as long as
the processor is active. This value is relaxed to 400 to
allow a lower power CSWR state during cpuidle path.

The context is saved and restored properly when suspending
the remote processor.

Change-Id: I89fd125f2244ae1691843c3c078aa6314a7ae8a6
Signed-off-by: Miguel Vadillo <vadillo@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
mm: make swapin readahead skip over holes

Ever since abandoning the virtual scan of processes, for scalability
reasons, swap space has been a little more fragmented than before.  This
can lead to the situation where a large memory user is killed, swap space
ends up full of "holes" and swapin readahead is totally ineffective.

On my home system, after killing a leaky firefox it took over an hour to
page just under 2GB of memory back in, slowing the virtual machines down
to a crawl.

This patch makes swapin readahead simply skip over holes, instead of
stopping at them.  This allows the system to swap things back in at rates
of several MB/second, instead of a few hundred kB/second.

The checks done in valid_swaphandles are already done in
read_swap_cache_async as well, allowing us to remove a fair amount of
code.

[akpm@linux-foundation.org: fix it for page_cluster >= 32]
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Adrian Drzewiecki <z@drze.net>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
swap: allow swap readahead to be merged

Swap readahead works fine, but the I/O to disk is almost always done in
page size requests, despite the fact that readahead submits
1<<page-cluster pages at a time.

On older kernels the old per device plugging behavior might have captured
this and merged the requests, but currently all comes down to much more
I/Os than required.

On a single device this might not be an issue, but as soon as a server
runs on shared san resources savin I/Os not only improves swapin
throughput but also provides a lower resource utilization.

With a load running KVM in a lot of memory overcommitment (the hot memory
is 1.5 times the host memory) swapping throughput improves significantly
and the lead feels more responsive as well as achieves more throughput.

In a test setup with 16 swap disks running blocktrace on one of those disks
shows the improved merging:
Prior:
Reads Queued:     560,888,    2,243MiB  Writes Queued:     226,242,  904,968KiB
Read Dispatches:  544,701,    2,243MiB  Write Dispatches:  159,318,  904,968KiB
Reads Requeued:         0               Writes Requeued:         0
Reads Completed:  544,716,    2,243MiB  Writes Completed:  159,321,  904,980KiB
Read Merges:       16,187,   64,748KiB  Write Merges:       61,744,  246,976KiB
IO unplugs:       149,614               Timer unplugs:       2,940

With the patch:
Reads Queued:     734,315,    2,937MiB  Writes Queued:     300,188,    1,200MiB
Read Dispatches:  214,972,    2,937MiB  Write Dispatches:  215,176,    1,200MiB
Reads Requeued:         0               Writes Requeued:         0
Reads Completed:  214,971,    2,937MiB  Writes Completed:  215,177,    1,200MiB
Read Merges:      519,343,    2,077MiB  Write Merges:       73,325,  293,300KiB
IO unplugs:       337,130               Timer unplugs:      11,184

I got ~10% to ~40% more throughput in my cases and at the same time much
lower cpu consumption when broken down per transferred kilobyte (the
majority of that due to saved interrupts and better cache handling).  In a
shared SAN others might get an additional benefit as well, because this
now causes less protocol overhead.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
softirq: reduce latencies

In various network workloads, __do_softirq() latencies can be up
to 20 ms if HZ=1000, and 200 ms if HZ=100.

This is because we iterate 10 times in the softirq dispatcher,
and some actions can consume a lot of cycles.

This patch changes the fallback to ksoftirqd condition to :

- A time limit of 2 ms.
- need_resched() being set on current task

When one of this condition is met, we wakeup ksoftirqd for further
softirq processing if we still have pending softirqs.

Using need_resched() as the only condition can trigger RCU stalls,
as we can keep BH disabled for too long.

I ran several benchmarks and got no significant difference in
throughput, but a very significant reduction of latencies (one order
of magnitude) :

In following bench, 200 antagonist "netperf -t TCP_RR" are started in
background, using all available cpus.

Then we start one "netperf -t TCP_RR", bound to the cpu handling the NIC
IRQ (hard+soft)

Before patch :

# netperf -H 7.7.7.84 -t TCP_RR -T2,2 -- -k
RT_LATENCY,MIN_LATENCY,MAX_LATENCY,P50_LATENCY,P90_LATENCY,P99_LATENCY,MEAN_LATENCY,STDDEV_LATENCY
MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET
to 7.7.7.84 () port 0 AF_INET : first burst 0 : cpu bind
RT_LATENCY=550110.424
MIN_LATENCY=146858
MAX_LATENCY=997109
P50_LATENCY=305000
P90_LATENCY=550000
P99_LATENCY=710000
MEAN_LATENCY=376989.12
STDDEV_LATENCY=184046.92

After patch :

# netperf -H 7.7.7.84 -t TCP_RR -T2,2 -- -k
RT_LATENCY,MIN_LATENCY,MAX_LATENCY,P50_LATENCY,P90_LATENCY,P99_LATENCY,MEAN_LATENCY,STDDEV_LATENCY
MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET
to 7.7.7.84 () port 0 AF_INET : first burst 0 : cpu bind
RT_LATENCY=40545.492
MIN_LATENCY=9834
MAX_LATENCY=78366
P50_LATENCY=33583
P90_LATENCY=59000
P99_LATENCY=69000
MEAN_LATENCY=38364.67
STDDEV_LATENCY=12865.26

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Miller <davem@davemloft.net>
Cc: Tom Herbert <therbert@google.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
sync: don't block the flusher thread waiting on IO

When sync does it's WB_SYNC_ALL writeback, it issues data Io and
then immediately waits for IO completion. This is done in the
context of the flusher thread, and hence completely ties up the
flusher thread for the backing device until all the dirty inodes
have been synced. On filesystems that are dirtying inodes constantly
and quickly, this means the flusher thread can be tied up for
minutes per sync call and hence badly affect system level write IO
performance as the page cache cannot be cleaned quickly.

We already have a wait loop for IO completion for sync(2), so cut
this out of the flusher thread and delegate it to wait_sb_inodes().
Hence we can do rapid IO submission, and then wait for it all to
complete.

Effect of sync on fsmark before the patch:

FSUse%        Count         Size    Files/sec     App Overhead
.....
     0       640000         4096      35154.6          1026984
     0       720000         4096      36740.3          1023844
     0       800000         4096      36184.6           916599
     0       880000         4096       1282.7          1054367
     0       960000         4096       3951.3           918773
     0      1040000         4096      40646.2           996448
     0      1120000         4096      43610.1           895647
     0      1200000         4096      40333.1           921048

And a single sync pass took:

  real    0m52.407s
  user    0m0.000s
  sys     0m0.090s

After the patch, there is no impact on fsmark results, and each
individual sync(2) operation run concurrently with the same fsmark
workload takes roughly 7s:

  real    0m6.930s
  user    0m0.000s
  sys     0m0.039s

IOWs, sync is 7-8x faster on a busy filesystem and does not have an
adverse impact on ongoing async data write operations.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	fs/fs-writeback.c
	include/linux/writeback.h

boype: adapted to 3.0 kernel