With blkio_policy[], blkio_list is redundant and hinders with
per-queue policy activation. Remove it. Also, replace
blkio_list_lock with a mutex blkcg_pol_mutex and let it protect the
whole [un]registration.
This is to prepare for per-queue policy activation and doesn't cause
any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that all stat handling code lives in policy implementations,
there's no need to encode policy ID in cft->private.
* Export blkcg_prfill_[rw]stat() from blkcg, remove
blkcg_print_[rw]stat(), and implement cfqg_print_[rw]stat() which
use hard-code BLKIO_POLICY_PROP.
* Use cft->private for offset of the target field directly and drop
BLKCG_STAT_{PRIV|POL|OFF}().
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that all conf and stat fields are moved into policy specific
blkio_policy_data->pdata areas, there's no reason to use
blkio_policy_data itself in prfill functions. Pass around @pd->pdata
instead of @pd.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkio_cgroup_conf->iops and ->bps are owned by blk-throttle and has no
reason to be defined in blkcg core. Drop them and let conf setting
functions directly manipulate throtl_grp->bps[] and ->iops[].
This makes blkio_group_conf empty. Drop it.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkio_group_conf->weight is owned by cfq and has no reason to be
defined in blkcg core. Replace it with cfq_group->dev_weight and let
conf setting functions directly set it. If dev_weight is zero, the
cfqg doesn't have device specific weight configured.
Also, rename BLKIO_WEIGHT_* constants to CFQ_WEIGHT_* and rename
blkio_cgroup->weight to blkio_cgroup->cfq_weight. We eventually want
per-policy storage in blkio_cgroup but just mark the ownership of the
field for now.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkio_group_stats_cpu is used only by blk-throtl and has no reason to
be defined in blkcg core.
* Move blkio_group_stats_cpu to blk-throttle.c and rename it to
tg_stats_cpu.
* blkg_policy_data->stats_cpu is replaced with throtl_grp->stats_cpu.
prfill functions updated accordingly.
* All related macros / functions are renamed so that they have tg_
prefix and the unnecessary @pol arguments are dropped.
* Per-cpu stats allocation code is also moved from blk-cgroup.c to
blk-throttle.c and gets simplified to only deal with
BLKIO_POLICY_THROTL. percpu stat free is performed by the exit
method throtl_exit_blkio_group().
* throtl_reset_group_stats() implemented for
blkio_reset_group_stats_fn method so that tg->stats_cpu can be
reset.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkio_group_stats contains only fields used by cfq and has no reason
to be defined in blkcg core.
* Move blkio_group_stats to cfq-iosched.c and rename it to cfqg_stats.
* blkg_policy_data->stats is replaced with cfq_group->stats.
blkg_prfill_[rw]stat() are updated to use offset against pd->pdata
instead.
* All related macros / functions are renamed so that they have cfqg_
prefix and the unnecessary @pol arguments are dropped.
* All stat functions now take cfq_group * instead of blkio_group *.
* lockdep assertion on queue lock dropped. Elevator runs under queue
lock by default. There isn't much to be gained by adding lockdep
assertions at stat function level.
* cfqg_stats_reset() implemented for blkio_reset_group_stats_fn method
so that cfqg->stats can be reset.
Signed-off-by: Tejun Heo <tj@kernel.org>
Add blkio_policy_ops->blkio_exit_group_fn() and
->blkio_reset_group_stats_fn(). These will be used to further
modularize blkcg policy implementation.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkio_group_stats_cpu is used to count dispatch stats using per-cpu
counters. This is used by both blk-throtl and cfq-iosched but the
sharing is rather silly.
* cfq-iosched doesn't need per-cpu dispatch stats. cfq always updates
those stats while holding queue_lock.
* blk-throtl needs per-cpu dispatch stats but only service_bytes and
serviced. It doesn't make use of sectors.
This patch makes cfq add and use global stats for service_bytes,
serviced and sectors, removes per-cpu sectors counter and moves
per-cpu stat printing code to blk-throttle.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
As with conf/stats file handling code, there's no reason for stat
update code to live in blkcg core with policies calling into update
them. The current organization is both inflexible and complex.
This patch moves stat update code to specific policies. All
blkiocg_update_*_stats() functions which deal with BLKIO_POLICY_PROP
stats are collapsed into their cfq_blkiocg_update_*_stats()
counterparts. blkiocg_update_dispatch_stats() is used by both
policies and duplicated as throtl_update_dispatch_stats() and
cfq_blkiocg_update_dispatch_stats(). This will be cleaned up later.
Signed-off-by: Tejun Heo <tj@kernel.org>
block/cfq.h contains some functions which interact with blkcg;
however, this is only part of it and cfq-iosched.c already has quite
some #ifdef CONFIG_CFQ_GROUP_IOSCHED. With conf/stat handling being
moved to specific policies, having these relay functions isolated in
cfq.h doesn't make much sense. Collapse cfq.h into cfq-iosched.c for
now. Let's split blkcg support properly later if necessary.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkcg conf/stat handling is convoluted in that details which belong to
specific policy implementations are all out in blkcg core and then
policies hook into core layer to access and manipulate confs and
stats. This sadly achieves both inflexibility (confs/stats can't be
modified without messing with blkcg core) and complexity (all the
call-ins and call-backs).
The previous patches restructured conf and stat handling code such
that they can be separated out. This patch relocates the file
handling part. All conf/stat file handling code which belongs to
BLKIO_POLICY_PROP is moved to cfq-iosched.c and all
BKLIO_POLICY_THROTL code to blk-throtl.c.
The move is verbatim except for blkio_update_group_{weight|bps|iops}()
callbacks which relays conf changes to policies. The configuration
settings are handled in policies themselves so the relaying isn't
necessary. Conf setting functions are modified to directly call
per-policy update functions and the relaying mechanism is dropped.
Signed-off-by: Tejun Heo <tj@kernel.org>
Add blkiop->cftypes which is added and removed together with the
policy. This will be used to move conf/stat handling to the policies.
Signed-off-by: Tejun Heo <tj@kernel.org>
conf/stat handling is about to be moved to policy implementation from
blkcg core. Export conf/stat helpers from blkcg core so that
blk-throttle and cfq-iosched can use them.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkg_conf_prep() implements "MAJ:MIN VAL" parsing manually, which is
unnecessary. Just use sscanf("%u:%u %llu"). This might not reject
some malformed input (extra input at the end) but we don't care.
Signed-off-by: Tejun Heo <tj@kernel.org>
As part of userland interface restructuring, this patch updates
per-blkio_group configuration setting. Instead of funneling
everything through a master function which has hard-coded cases for
each config file it may handle, the common part is factored into
blkg_conf_prep() and blkg_conf_finish() and different configuration
setters are implemented using the helpers.
While this doesn't result in immediate LOC reduction, this enables
further cleanups and more modular implementation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Similarly to the previous stat restructuring, this patch restructures
conf printing code such that,
* Conf printing uses the same helpers as stat.
* Printing function doesn't require hardcoded switching on the config
being printed. Note that this isn't complete yet for throttle
confs. The next patch will convert setting for these confs and will
complete the transition.
* Printing uses read_seq_string callback (other methods will be phased
out).
Note that blkio_group_conf.iops[2] is changed to u64 so that they can
be manipulated with the same functions. This is transitional and will
go away later.
After this patch, per-device configurations - weight, bps and iops -
use __blkg_prfill_u64() for printing which uses white space as
delimiter instead of tab.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkiocg_file_write_u64() has single switch case. Drop
blkiocg_file_write_u64(), rename blkio_weight_write() to
blkcg_set_weight() and use it directly for .write_u64 callback.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkcg stats handling is a mess. None of the stats has much to do with
blkcg core but they are all implemented in blkcg core. Code sharing
is achieved by mixing common code with hard-coded cases for each stat
counter.
This patch restructures statistics printing such that
* Common logic exists as helper functions and specific print functions
use the helpers to implement specific cases.
* Printing functions serving multiple counters don't require hardcoded
switching on specific counters.
* Printing uses read_seq_string callback (other methods will be phased
out).
This change enables further cleanups and relocating stats code to the
policy implementation it belongs to.
Signed-off-by: Tejun Heo <tj@kernel.org>
blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values
on 32bit archs and some stat counters have subtypes to distinguish
read/writes and sync/async IOs. The stat code paths are confusing and
involve a lot of going back and forth between blkcg core and specific
policy implementations, and synchronization and subtype handling are
open coded in blkcg core.
This patch introduces struct blkg_stat and blkg_rwstat which, with
accompanying operations, encapsulate stat updating and accessing with
proper synchronization.
blkg_stat is simple u64 counter with 64bit read-access protection.
blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw
flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and
replaces stat_sub_type indexed arrays.
All counters in blkio_group_stats and blkio_group_stats_cpu are
replaced with either blkg_stat or blkg_rwstat along with all users.
This does add one u64_stats_sync per counter and increase stats_sync
operations but they're empty/noops on 64bit archs and blkcg doesn't
have too many counters, especially with DEBUG_BLK_CGROUP off.
While the currently resulting code isn't necessarily simpler at the
moment, this will enable further clean up of blkcg stats code.
- BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to
BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}.
- blkg_stat_add() replaces blkio_add_stat() and
blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the
latter function no longer exists. It's *way* better to have
underflowed stat counters than oopsing.
- blkio_group_stats->dequeue is now a proper u64 stat counter instead
of ulong.
- reset_stats() updated to clear each stat counters individually and
BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed.
- Some functions reconstruct rw flags from direction and sync
booleans. This will be removed by future patches.
Signed-off-by: Tejun Heo <tj@kernel.org>
BLKIO_STAT_CPU_SECTORS doesn't need read/write/sync/async subcounters
and is counted by blkio_group_stats_cpu->sectors; however, it still
holds a member in blkio_group_stats_cpu->stat_arr_cpu.
Rearrange stat_type_cpu and define BLKIO_STAT_CPU_ARR_NR and use it
for stat_arr_cpu[] size so that only SERVICE_BYTES and SERVICED have
subcounters.
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup/for-3.5 contains the following changes which blk-cgroup needs
to proceed with the on-going cleanup.
* Dynamic addition and removal of cftypes to make config/stat file
handling modular for policies.
* cgroup removal update to not wait for css references to drain to fix
blkcg removal hang caused by cfq caching cfqgs.
Pull in cgroup/for-3.5 into block/for-3.5/core. This causes the
following conflicts in block/blk-cgroup.c.
* 761b3ef50e "cgroup: remove cgroup_subsys argument from callbacks"
conflicts with blkiocg_pre_destroy() addition and blkiocg_attach()
removal. Resolved by removing @subsys from all subsys methods.
* 676f7c8f84 "cgroup: relocate cftype and cgroup_subsys definitions in
controllers" conflicts with ->pre_destroy() and ->attach() updates
and removal of modular config. Resolved by dropping forward
declarations of the methods and applying updates to the relocated
blkio_subsys.
* 4baf6e3325 "cgroup: convert all non-memcg controllers to the new
cftype interface" builds upon the previous item. Resolved by adding
->base_cftypes to the relocated blkio_subsys.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, cgroup removal tries to drain all css references. If there
are active css references, the removal logic waits and retries
->pre_detroy() until either all refs drop to zero or removal is
cancelled.
This semantics is unusual and adds non-trivial complexity to cgroup
core and IMHO is fundamentally misguided in that it couples internal
implementation details (references to internal data structure) with
externally visible operation (rmdir). To userland, this is a behavior
peculiarity which is unnecessary and difficult to expect (css refs is
otherwise invisible from userland), and, to policy implementations,
this is an unnecessary restriction (e.g. blkcg wants to hold css refs
for caching purposes but can't as that becomes visible as rmdir hang).
Unfortunately, memcg currently depends on ->pre_destroy() retrials and
cgroup removal vetoing and can't be immmediately switched to the new
behavior. This patch introduces the new behavior of not waiting for
css refs to drain and maintains the old behavior for subsystems which
have __DEPRECATED_clear_css_refs set.
Once, memcg is updated, we can drop the code paths for the old
behavior as proposed in the following patch. Note that the following
patch is incorrect in that dput work item is in cgroup and may lose
some of dputs when multiples css's are released back-to-back, and
__css_put() triggers check_for_release() when refcnt reaches 0 instead
of 1; however, it shows what part can be removed.
http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251
Note that, in not-too-distant future, cgroup core will start emitting
warning messages for subsys which require the old behavior, so please
get moving.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tejun Heo