Async I/O latency to a ssd greatly increased, 34% gain (Creds: kleikamp)
mm: writeback: every 500ms the writeback daemon kicks in and flushes the dirty pages into disk.

Thats not very pleasant for performance and *maybe* battery. This patch disables the writeback function while the screen is on,
and enables it back when the screen is off to flush all the dirty pages.
In my real world usage testing I notice a slight bump in smoothness and performance while using the device.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Revert "block: row: fix one of the magic values. Thanks @osm0sis."

This reverts commit 585ca5f20c3aa4b32393433c899e1ae86d7b091c.
Revert "block: row: hardcode magic values. thx franciscofranco"

This reverts commit c1fa6f9f21d23caaa731feda47ecaded72551f14.
block: row-iosched idling triggered by readahead pages

In the current implementation idling is triggered only by request
insertion frequency. This heuristic is not very accurate and may hit
random requests that shouldn't trigger idling. This patch uses the
PG_readahead flag in struct page's flags, which indicates that the page
is part of a readahead window, to start idling upon dispatch of a request
associated with a readahead page.

The above readehead flag is used together with the existing
insertion-frequency trigger. The frequency timer will catch read requests
which are not part of a readahead window, but are still part of a
sequential stream (and therefore dispatched in small time intervals).

Change-Id: Icb7145199c007408de3f267645ccb842e051fd00
Signed-off-by: Lee Susman <lsusman@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
mm: change initial readahead window size calculation

Change the logic which determines the initial readahead window size
such that for small requests (one page) the initial window size
will be x4 the size of the original request, regardless of the
VM_MAX_READAHEAD value. This prevents a rapid ramp-up
that could be caused due to increasing VM_MAX_READAHEAD.

Change-Id: I93d59c515d7e6c6d62348790980ff7bd4f434997
Signed-off-by: Lee Susman <lsusman@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
mm: pass readahead info down to the i/o scheduler

Some i/o schedulers (i.e. row-iosched, cfq-iosched) deploy an idling
algorithm in order to be better synced with the readahead algorithm.
Idling is a prediction algorithm for incoming read requests.

In this patch we mark pages which are part of a readahead window, by
setting a newly introduced flag. With this flag, the i/o scheduler can
identify a request which is associated with a readahead page. This
enables the i/o scheduler's idling mechanism to be en-sync with the
readahead mechanism and, in turn, can increase read throughput.

Change-Id: I0654f23315b6d19d71bcc9cc029c6b281a44b196
Signed-off-by: Lee Susman <lsusman@codeaurora.org>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
thermal: tsens8960: Increase the polling rate

Change the polling rate at which the sensors temperature
is read from 1 second to .25 seconds. On faster parts
there is a need to poll the temperature at a higher
frequency to improve reporting temperature changes.

Change-Id: I10049707c3e55316597fff72fbd00246cd29bed3
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
config: Update hells_defconfig