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authorOlof Johansson <olof@lixom.net>2012-09-12 22:34:11 -0700
committerOlof Johansson <olof@lixom.net>2012-09-12 22:34:11 -0700
commit025c95a6826ad8acfe871f33c2fa9208beeb38df (patch)
tree220fe156ff60db13bd3a1319f5e20d6b723de5f4 /Documentation
parent0558d7a8ed44e6e53aadb04d2e23145efb2aa8a4 (diff)
parent7f744b17140af1a9c8804a1c81c9dae6bb52a7fb (diff)
Merge branch 'clk' of git://github.com/hzhuang1/linux into next/cleanup
* 'clk' of git://github.com/hzhuang1/linux: ARM: mmp: remove unused definition in APBC and APMU ARM: mmp: move mmp2 clock definition to separated file arm: mmp: move pxa910 clock definition to separated file arm: mmp: move pxa168 clock definition to separated file arm: mmp: make private clock definition exclude from common clock + Linux 3.6-rc4
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/block/00-INDEX10
-rw-r--r--Documentation/block/cfq-iosched.txt77
-rw-r--r--Documentation/block/queue-sysfs.txt64
-rw-r--r--Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt8
-rw-r--r--Documentation/watchdog/src/watchdog-test.c2
5 files changed, 154 insertions, 7 deletions
diff --git a/Documentation/block/00-INDEX b/Documentation/block/00-INDEX
index d111e3b23db0..d18ecd827c40 100644
--- a/Documentation/block/00-INDEX
+++ b/Documentation/block/00-INDEX
@@ -3,15 +3,21 @@
biodoc.txt
- Notes on the Generic Block Layer Rewrite in Linux 2.5
capability.txt
- - Generic Block Device Capability (/sys/block/<disk>/capability)
+ - Generic Block Device Capability (/sys/block/<device>/capability)
+cfq-iosched.txt
+ - CFQ IO scheduler tunables
+data-integrity.txt
+ - Block data integrity
deadline-iosched.txt
- Deadline IO scheduler tunables
ioprio.txt
- Block io priorities (in CFQ scheduler)
+queue-sysfs.txt
+ - Queue's sysfs entries
request.txt
- The members of struct request (in include/linux/blkdev.h)
stat.txt
- - Block layer statistics in /sys/block/<dev>/stat
+ - Block layer statistics in /sys/block/<device>/stat
switching-sched.txt
- Switching I/O schedulers at runtime
writeback_cache_control.txt
diff --git a/Documentation/block/cfq-iosched.txt b/Documentation/block/cfq-iosched.txt
index 6d670f570451..d89b4fe724d7 100644
--- a/Documentation/block/cfq-iosched.txt
+++ b/Documentation/block/cfq-iosched.txt
@@ -1,3 +1,14 @@
+CFQ (Complete Fairness Queueing)
+===============================
+
+The main aim of CFQ scheduler is to provide a fair allocation of the disk
+I/O bandwidth for all the processes which requests an I/O operation.
+
+CFQ maintains the per process queue for the processes which request I/O
+operation(syncronous requests). In case of asynchronous requests, all the
+requests from all the processes are batched together according to their
+process's I/O priority.
+
CFQ ioscheduler tunables
========================
@@ -25,6 +36,72 @@ there are multiple spindles behind single LUN (Host based hardware RAID
controller or for storage arrays), setting slice_idle=0 might end up in better
throughput and acceptable latencies.
+back_seek_max
+-------------
+This specifies, given in Kbytes, the maximum "distance" for backward seeking.
+The distance is the amount of space from the current head location to the
+sectors that are backward in terms of distance.
+
+This parameter allows the scheduler to anticipate requests in the "backward"
+direction and consider them as being the "next" if they are within this
+distance from the current head location.
+
+back_seek_penalty
+-----------------
+This parameter is used to compute the cost of backward seeking. If the
+backward distance of request is just 1/back_seek_penalty from a "front"
+request, then the seeking cost of two requests is considered equivalent.
+
+So scheduler will not bias toward one or the other request (otherwise scheduler
+will bias toward front request). Default value of back_seek_penalty is 2.
+
+fifo_expire_async
+-----------------
+This parameter is used to set the timeout of asynchronous requests. Default
+value of this is 248ms.
+
+fifo_expire_sync
+----------------
+This parameter is used to set the timeout of synchronous requests. Default
+value of this is 124ms. In case to favor synchronous requests over asynchronous
+one, this value should be decreased relative to fifo_expire_async.
+
+slice_async
+-----------
+This parameter is same as of slice_sync but for asynchronous queue. The
+default value is 40ms.
+
+slice_async_rq
+--------------
+This parameter is used to limit the dispatching of asynchronous request to
+device request queue in queue's slice time. The maximum number of request that
+are allowed to be dispatched also depends upon the io priority. Default value
+for this is 2.
+
+slice_sync
+----------
+When a queue is selected for execution, the queues IO requests are only
+executed for a certain amount of time(time_slice) before switching to another
+queue. This parameter is used to calculate the time slice of synchronous
+queue.
+
+time_slice is computed using the below equation:-
+time_slice = slice_sync + (slice_sync/5 * (4 - prio)). To increase the
+time_slice of synchronous queue, increase the value of slice_sync. Default
+value is 100ms.
+
+quantum
+-------
+This specifies the number of request dispatched to the device queue. In a
+queue's time slice, a request will not be dispatched if the number of request
+in the device exceeds this parameter. This parameter is used for synchronous
+request.
+
+In case of storage with several disk, this setting can limit the parallel
+processing of request. Therefore, increasing the value can imporve the
+performace although this can cause the latency of some I/O to increase due
+to more number of requests.
+
CFQ IOPS Mode for group scheduling
===================================
Basic CFQ design is to provide priority based time slices. Higher priority
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index 6518a55273e7..e54ac1d53403 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -9,20 +9,71 @@ These files are the ones found in the /sys/block/xxx/queue/ directory.
Files denoted with a RO postfix are readonly and the RW postfix means
read-write.
+add_random (RW)
+----------------
+This file allows to trun off the disk entropy contribution. Default
+value of this file is '1'(on).
+
+discard_granularity (RO)
+-----------------------
+This shows the size of internal allocation of the device in bytes, if
+reported by the device. A value of '0' means device does not support
+the discard functionality.
+
+discard_max_bytes (RO)
+----------------------
+Devices that support discard functionality may have internal limits on
+the number of bytes that can be trimmed or unmapped in a single operation.
+The discard_max_bytes parameter is set by the device driver to the maximum
+number of bytes that can be discarded in a single operation. Discard
+requests issued to the device must not exceed this limit. A discard_max_bytes
+value of 0 means that the device does not support discard functionality.
+
+discard_zeroes_data (RO)
+------------------------
+When read, this file will show if the discarded block are zeroed by the
+device or not. If its value is '1' the blocks are zeroed otherwise not.
+
hw_sector_size (RO)
-------------------
This is the hardware sector size of the device, in bytes.
+iostats (RW)
+-------------
+This file is used to control (on/off) the iostats accounting of the
+disk.
+
+logical_block_size (RO)
+-----------------------
+This is the logcal block size of the device, in bytes.
+
max_hw_sectors_kb (RO)
----------------------
This is the maximum number of kilobytes supported in a single data transfer.
+max_integrity_segments (RO)
+---------------------------
+When read, this file shows the max limit of integrity segments as
+set by block layer which a hardware controller can handle.
+
max_sectors_kb (RW)
-------------------
This is the maximum number of kilobytes that the block layer will allow
for a filesystem request. Must be smaller than or equal to the maximum
size allowed by the hardware.
+max_segments (RO)
+-----------------
+Maximum number of segments of the device.
+
+max_segment_size (RO)
+---------------------
+Maximum segment size of the device.
+
+minimum_io_size (RO)
+--------------------
+This is the smallest preferred io size reported by the device.
+
nomerges (RW)
-------------
This enables the user to disable the lookup logic involved with IO
@@ -45,11 +96,24 @@ per-block-cgroup request pool. IOW, if there are N block cgroups,
each request queue may have upto N request pools, each independently
regulated by nr_requests.
+optimal_io_size (RO)
+--------------------
+This is the optimal io size reported by the device.
+
+physical_block_size (RO)
+------------------------
+This is the physical block size of device, in bytes.
+
read_ahead_kb (RW)
------------------
Maximum number of kilobytes to read-ahead for filesystems on this block
device.
+rotational (RW)
+---------------
+This file is used to stat if the device is of rotational type or
+non-rotational type.
+
rq_affinity (RW)
----------------
If this option is '1', the block layer will migrate request completions to the
diff --git a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt
index 70cd49b1caa8..1dd622546d06 100644
--- a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt
+++ b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt
@@ -10,8 +10,8 @@ Required properties:
- compatible : Should be "fsl,<chip>-esdhc"
Optional properties:
-- fsl,cd-internal : Indicate to use controller internal card detection
-- fsl,wp-internal : Indicate to use controller internal write protection
+- fsl,cd-controller : Indicate to use controller internal card detection
+- fsl,wp-controller : Indicate to use controller internal write protection
Examples:
@@ -19,8 +19,8 @@ esdhc@70004000 {
compatible = "fsl,imx51-esdhc";
reg = <0x70004000 0x4000>;
interrupts = <1>;
- fsl,cd-internal;
- fsl,wp-internal;
+ fsl,cd-controller;
+ fsl,wp-controller;
};
esdhc@70008000 {
diff --git a/Documentation/watchdog/src/watchdog-test.c b/Documentation/watchdog/src/watchdog-test.c
index 73ff5cc93e05..3da822967ee0 100644
--- a/Documentation/watchdog/src/watchdog-test.c
+++ b/Documentation/watchdog/src/watchdog-test.c
@@ -31,7 +31,7 @@ static void keep_alive(void)
* or "-e" to enable the card.
*/
-void term(int sig)
+static void term(int sig)
{
close(fd);
fprintf(stderr, "Stopping watchdog ticks...\n");