linux.git/Documentation/block, branch v3.12-rc2

block: support embedded device command line partition

2013-09-11T22:56:57+00:00

Read block device partition table from command line.  The partition used
for fixed block device (eMMC) embedded device.  It is no MBR, save
storage space.  Bootloader can be easily accessed by absolute address of
data on the block device.  Users can easily change the partition.

This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
About the partition verbose reference
"Documentation/block/cmdline-partition.txt"

[akpm@linux-foundation.org: fix printk text]
[yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()]
Signed-off-by: Cai Zhiyong 
Cc: Karel Zak 
Cc: "Wanglin (Albert)" 
Cc: Marius Groeger 
Cc: David Woodhouse 
Cc: Jens Axboe 
Cc: Brian Norris 
Cc: Artem Bityutskiy 
Signed-off-by: Wei Yongjun 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

doc: Fix typo in doucmentations

2013-07-25T10:34:15+00:00

Correct typo (double words) in documentations.

Signed-off-by: Masanari Iida 
Acked-by: Randy Dunlap 
Signed-off-by: Jiri Kosina

doc: fix misspellings with 'codespell' tool

2013-05-28T10:02:12+00:00

Signed-off-by: Anatol Pomozov 
Signed-off-by: Jiri Kosina

Documentation: cfq-iosched: update documentation help for cfq tunables

2013-04-09T12:57:06+00:00

Add the documentation text for latency, target_latency & group_idle
tunnable parameters in the block/cfq-iosched.txt.
Also fix few typo(spelling) mistakes.

Signed-off-by: Namjae Jeon 
Signed-off-by: Amit Sahrawat 

Language somewhat modified by Jens.

Signed-off-by: Jens Axboe

cfq-iosched: enable full blkcg hierarchy support

2013-01-09T16:05:11+00:00

With the previous two patches, all cfqg scheduling decisions are based
on vfraction and ready for hierarchy support.  The only thing which
keeps the behavior flat is cfqg_flat_parent() which makes vfraction
calculation consider all non-root cfqgs children of the root cfqg.

Replace it with cfqg_parent() which returns the real parent.  This
enables full blkcg hierarchy support for cfq-iosched.  For example,
consider the following hierarchy.

        root
      /      \
   A:500      B:250
  /     \
 AA:500  AB:1000

For simplicity, let's say all the leaf nodes have active tasks and are
on service tree.  For each leaf node, vfraction would be

 AA: (500  / 1500) * (500 / 750) =~ 0.2222
 AB: (1000 / 1500) * (500 / 750) =~ 0.4444
  B:                 (250 / 750) =~ 0.3333

and vdisktime will be distributed accordingly.  For more detail,
please refer to Documentation/block/cfq-iosched.txt.

v2: cfq-iosched.txt updated to describe group scheduling as suggested
    by Vivek.

v3: blkio-controller.txt updated.

Signed-off-by: Tejun Heo 
Acked-by: Vivek Goyal

block: Kill bi_destructor

2012-09-09T08:35:39+00:00

Now that we've got generic code for freeing bios allocated from bio
pools, this isn't needed anymore.

This patch also makes bio_free() static, since without bi_destructor
there should be no need for it to be called anywhere else.

bio_free() is now only called from bio_put, so we can refactor those a
bit - move some code from bio_put() to bio_free() and kill the redundant
bio->bi_next = NULL.

v5: Switch to BIO_KMALLOC_POOL ((void *)~0), per Boaz
v6: BIO_KMALLOC_POOL now NULL, drop bio_free's EXPORT_SYMBOL
v7: No #define BIO_KMALLOC_POOL anymore

Signed-off-by: Kent Overstreet 
CC: Jens Axboe 
Signed-off-by: Jens Axboe

Documentation: update tunable options in block/cfq-iosched.txt

2012-08-09T13:28:05+00:00

Update tunable options in block/cfq-iosched.txt.

Signed-off-by: Namjae Jeon 
Signed-off-by: Jens Axboe

Documentation: update tunable options in block/cfq-iosched.txt

2012-08-09T13:27:29+00:00

Update tunable options in block/cfq-iosched.txt.

Signed-off-by: Namjae Jeon 
Signed-off-by: Jens Axboe

Documentation: update missing index files in block/00-INDEX

2012-08-09T13:27:28+00:00

Update missing index files in block/00-INDEX.

Signed-off-by: Namjae Jeon 
Signed-off-by: Jens Axboe

blkcg: implement per-blkg request allocation

2012-06-26T22:42:49+00:00

Currently, request_queue has one request_list to allocate requests
from regardless of blkcg of the IO being issued.  When the unified
request pool is used up, cfq proportional IO limits become meaningless
- whoever grabs the next request being freed wins the race regardless
of the configured weights.

This can be easily demonstrated by creating a blkio cgroup w/ very low
weight, put a program which can issue a lot of random direct IOs there
and running a sequential IO from a different cgroup.  As soon as the
request pool is used up, the sequential IO bandwidth crashes.

This patch implements per-blkg request_list.  Each blkg has its own
request_list and any IO allocates its request from the matching blkg
making blkcgs completely isolated in terms of request allocation.

* Root blkcg uses the request_list embedded in each request_queue,
  which was renamed to @q->root_rl from @q->rq.  While making blkcg rl
  handling a bit harier, this enables avoiding most overhead for root
  blkcg.

* Queue fullness is properly per request_list but bdi isn't blkcg
  aware yet, so congestion state currently just follows the root
  blkcg.  As writeback isn't aware of blkcg yet, this works okay for
  async congestion but readahead may get the wrong signals.  It's
  better than blkcg completely collapsing with shared request_list but
  needs to be improved with future changes.

* After this change, each block cgroup gets a full request pool making
  resource consumption of each cgroup higher.  This makes allowing
  non-root users to create cgroups less desirable; however, note that
  allowing non-root users to directly manage cgroups is already
  severely broken regardless of this patch - each block cgroup
  consumes kernel memory and skews IO weight (IO weights are not
  hierarchical).

v2: queue-sysfs.txt updated and patch description udpated as suggested
    by Vivek.

v3: blk_get_rl() wasn't checking error return from
    blkg_lookup_create() and may cause oops on lookup failure.  Fix it
    by falling back to root_rl on blkg lookup failures.  This problem
    was spotted by Rakesh Iyer .

v4: Updated to accomodate 458f27a982 "block: Avoid missed wakeup in
    request waitqueue".  blk_drain_queue() now wakes up waiters on all
    blkg->rl on the target queue.

Signed-off-by: Tejun Heo 
Acked-by: Vivek Goyal 
Cc: Wu Fengguang 
Signed-off-by: Jens Axboe