user/sven/linux.git/block/elevator.c, branch v3.10

block: implement runtime pm strategy

2013-03-23T04:22:15Z

When a request is added: If device is suspended or is suspending and the request is not a PM request, resume the device. When the last request finishes: Call pm_runtime_mark_last_busy(). When pick a request: If device is resuming/suspending, then only PM request is allowed to go. The idea and API is designed by Alan Stern and described here: http://marc.info/?l=linux-scsi&m=133727953625963&w=2 Signed-off-by: Lin Ming Signed-off-by: Aaron Lu Acked-by: Alan Stern Signed-off-by: Jens Axboe

Merge branch 'for-3.9/core' of git://git.kernel.dk/linux-block

2013-02-28T20:52:24Z

Pull block IO core bits from Jens Axboe: "Below are the core block IO bits for 3.9. It was delayed a few days since my workstation kept crashing every 2-8h after pulling it into current -git, but turns out it is a bug in the new pstate code (divide by zero, will report separately). In any case, it contains: - The big cfq/blkcg update from Tejun and and Vivek. - Additional block and writeback tracepoints from Tejun. - Improvement of the should sort (based on queues) logic in the plug flushing. - _io() variants of the wait_for_completion() interface, using io_schedule() instead of schedule() to contribute to io wait properly. - Various little fixes. You'll get two trivial merge conflicts, which should be easy enough to fix up" Fix up the trivial conflicts due to hlist traversal cleanups (commit b67bfe0d42ca: "hlist: drop the node parameter from iterators"). * 'for-3.9/core' of git://git.kernel.dk/linux-block: (39 commits) block: remove redundant check to bd_openers() block: use i_size_write() in bd_set_size() cfq: fix lock imbalance with failed allocations drivers/block/swim3.c: fix null pointer dereference block: don't select PERCPU_RWSEM block: account iowait time when waiting for completion of IO request sched: add wait_for_completion_io[_timeout] writeback: add more tracepoints block: add block_{touch|dirty}_buffer tracepoint buffer: make touch_buffer() an exported function block: add @req to bio_{front|back}_merge tracepoints block: add missing block_bio_complete() tracepoint block: Remove should_sort judgement when flush blk_plug block,elevator: use new hashtable implementation cfq-iosched: add hierarchical cfq_group statistics cfq-iosched: collect stats from dead cfqgs cfq-iosched: separate out cfqg_stats_reset() from cfq_pd_reset_stats() blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock block: RCU free request_queue blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge() ...

hlist: drop the node parameter from iterators

2013-02-28T03:10:24Z

I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin Acked-by: Paul E. McKenney Signed-off-by: Sasha Levin Cc: Wu Fengguang Cc: Marcelo Tosatti Cc: Gleb Natapov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

block: don't request module during elevator init

2013-01-23T00:48:03Z

Block layer allows selecting an elevator which is built as a module to be selected as system default via kernel param "elevator=". This is achieved by automatically invoking request_module() whenever a new block device is initialized and the elevator is not available. This led to an interesting deadlock problem involving async and module init. Block device probing running off an async job invokes request_module(). While the module is being loaded, it performs async_synchronize_full() which ends up waiting for the async job which is already waiting for request_module() to finish, leading to deadlock. Invoking request_module() from deep in block device init path is already nasty in itself. It seems best to avoid these situations from the beginning by moving on-demand module loading out of block init path. The previous patch made sure that the default elevator module is loaded early during boot if available. This patch removes on-demand loading of the default elevator from elevator init path. As the module would have been loaded during boot, userland-visible behavior difference should be minimal. For more details, please refer to the following thread. http://thread.gmane.org/gmane.linux.kernel/1420814 v2: The bool parameter was named @request_module which conflicted with request_module(). This built okay w/ CONFIG_MODULES because request_module() was defined as a macro. W/o CONFIG_MODULES, it causes build breakage. Rename the parameter to @try_loading. Reported by Fengguang. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Arjan van de Ven Cc: Linus Torvalds Cc: Alex Riesen Cc: Fengguang Wu

init, block: try to load default elevator module early during boot

2013-01-18T22:05:56Z

This patch adds default module loading and uses it to load the default block elevator. During boot, it's called right after initramfs or initrd is made available and right before control is passed to userland. This ensures that as long as the modules are available in the usual places in initramfs, initrd or the root filesystem, the default modules are loaded as soon as possible. This will replace the on-demand elevator module loading from elevator init path. v2: Fixed build breakage when !CONFIG_BLOCK. Reported by kbuild test robot. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Arjan van de Ven Cc: Linus Torvalds Cc: Alex Riesen Cc: Fengguang We

block,elevator: use new hashtable implementation

2013-01-11T13:43:13Z

Switch elevator to use the new hashtable implementation. This reduces the amount of generic unrelated code in the elevator. This also removes the dymanic allocation of the hash table. The size of the table is constant so there's no point in paying the price of an extra dereference when accessing it. This patch depends on d9b482c ("hashtable: introduce a small and naive hashtable") which was merged in v3.6. Signed-off-by: Sasha Levin Signed-off-by: Jens Axboe

block: recursive merge requests

2012-11-09T07:44:27Z

In a workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1, a+3,.... When the requests are flushed to queue, a and a+1 are merged to (a, a+1), a+2 and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3) aren't merged. If we do recursive merge for such interleave access, some workloads throughput get improvement. A recent worload I'm checking on is swap, below change boostes the throughput around 5% ~ 10%. Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe

block: Clean up special command handling logic

2012-09-20T12:31:38Z

Remove special-casing of non-rw fs style requests (discard). The nomerge flags are consolidated in blk_types.h, and rq_mergeable() and bio_mergeable() have been modified to use them. bio_is_rw() is used in place of bio_has_data() a few places. This is done to to distinguish true reads and writes from other fs type requests that carry a payload (e.g. write same). Signed-off-by: Martin K. Petersen Acked-by: Mike Snitzer Signed-off-by: Jens Axboe

blkcg: implement per-queue policy activation

2012-04-20T08:06:06Z

All blkcg policies were assumed to be enabled on all request_queues. Due to various implementation obstacles, during the recent blkcg core updates, this was temporarily implemented as shooting down all !root blkgs on elevator switch and policy [de]registration combined with half-broken in-place root blkg updates. In addition to being buggy and racy, this meant losing all blkcg configurations across those events. Now that blkcg is cleaned up enough, this patch replaces the temporary implementation with proper per-queue policy activation. Each blkcg policy should call the new blkcg_[de]activate_policy() to enable and disable the policy on a specific queue. blkcg_activate_policy() allocates and installs policy data for the policy for all existing blkgs. blkcg_deactivate_policy() does the reverse. If a policy is not enabled for a given queue, blkg printing / config functions skip the respective blkg for the queue. blkcg_activate_policy() also takes care of root blkg creation, and cfq_init_queue() and blk_throtl_init() are updated accordingly. This replaces blkcg_bypass_{start|end}() and update_root_blkg_pd() unnecessary. Dropped. v2: cfq_init_queue() was returning uninitialized @ret on root_group alloc failure if !CONFIG_CFQ_GROUP_IOSCHED. Fixed. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe

block: implement bio_associate_current()

2012-03-06T20:27:24Z

IO scheduling and cgroup are tied to the issuing task via io_context and cgroup of %current. Unfortunately, there are cases where IOs need to be routed via a different task which makes scheduling and cgroup limit enforcement applied completely incorrectly. For example, all bios delayed by blk-throttle end up being issued by a delayed work item and get assigned the io_context of the worker task which happens to serve the work item and dumped to the default block cgroup. This is double confusing as bios which aren't delayed end up in the correct cgroup and makes using blk-throttle and cfq propio together impossible. Any code which punts IO issuing to another task is affected which is getting more and more common (e.g. btrfs). As both io_context and cgroup are firmly tied to task including userland visible APIs to manipulate them, it makes a lot of sense to match up tasks to bios. This patch implements bio_associate_current() which associates the specified bio with %current. The bio will record the associated ioc and blkcg at that point and block layer will use the recorded ones regardless of which task actually ends up issuing the bio. bio release puts the associated ioc and blkcg. It grabs and remembers ioc and blkcg instead of the task itself because task may already be dead by the time the bio is issued making ioc and blkcg inaccessible and those are all block layer cares about. elevator_set_req_fn() is updated such that the bio elvdata is being allocated for is available to the elevator. This doesn't update block cgroup policies yet. Further patches will implement the support. -v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in rq_ioc() to fix build breakage. Signed-off-by: Tejun Heo Cc: Vivek Goyal Cc: Kent Overstreet Signed-off-by: Jens Axboe