linux/Documentation/block, branch v3.6

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

2012-08-09T13:28:05Z

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

2012-08-09T13:27:29Z

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

2012-08-09T13:27:28Z

Update missing index files in block/00-INDEX. Signed-off-by: Namjae Jeon Signed-off-by: Jens Axboe

blkcg: implement per-blkg request allocation

2012-06-26T22:42:49Z

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

Documentation: drop as block elevator reference in switching-sched.txt

2011-11-04T19:01:48Z

Remove 'as' for as is no longer supported, and we can not use 'elevator=as' any more. Signed-off-by: Wang Sheng-Hui Signed-off-by: Randy Dunlap Cc: Jens Axboe Signed-off-by: Linus Torvalds

doc: fix broken references

2011-09-27T16:08:04Z

There are numerous broken references to Documentation files (in other Documentation files, in comments, etc.). These broken references are caused by typo's in the references, and by renames or removals of the Documentation files. Some broken references are simply odd. Fix these broken references, sometimes by dropping the irrelevant text they were part of. Signed-off-by: Paul Bolle Signed-off-by: Jiri Kosina

cfq-iosched: Add documentation about idling

2011-08-05T07:42:20Z

There are always questions about why CFQ is idling on various conditions. Recent ones is Christoph asking again why to idle on REQ_NOIDLE. His assertion is that XFS is relying more and more on workqueues and is concerned that CFQ idling on IO from every workqueue will impact XFS badly. So he suggested that I add some more documentation about CFQ idling and that can provide more clarity on the topic and also gives an opprotunity to poke a hole in theory and lead to improvements. So here is my attempt at that. Any comments are welcome. Signed-off-by: Vivek Goyal Signed-off-by: Jens Axboe

block: strict rq_affinity

2011-07-23T18:44:25Z

Some systems benefit from completions always being steered to the strict requester cpu rather than the looser "per-socket" steering that blk_cpu_to_group() attempts by default. This is because the first CPU in the group mask ends up being completely overloaded with work, while the others (including the original submitter) has power left to spare. Allow the strict mode to be set by writing '2' to the sysfs control file. This is identical to the scheme used for the nomerges file, where '2' is a more aggressive setting than just being turned on. echo 2 > /sys/block//queue/rq_affinity Cc: Christoph Hellwig Cc: Roland Dreier Tested-by: Dave Jiang Signed-off-by: Dan Williams Signed-off-by: Jens Axboe

Fix common misspellings

2011-03-31T14:26:23Z

Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi

block: remove per-queue plugging

2011-03-10T07:52:07Z

Code has been converted over to the new explicit on-stack plugging, and delay users have been converted to use the new API for that. So lets kill off the old plugging along with aops->sync_page(). Signed-off-by: Jens Axboe