Commit Graph

40 Commits

Author SHA1 Message Date
Christoph Hellwig
34fe7c0540 block: enumify ELEVATOR_*_MERGE
Switch these constants to an enum, and make let the compiler ensure that
all callers of blk_try_merge and elv_merge handle all potential values.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-08 13:43:06 -07:00
Jens Axboe
c51ca6cf54 block: move existing elevator ops to union
Prep patch for adding MQ ops as well, since doing anon unions with
named initializers doesn't work on older compilers.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17 10:03:33 -07:00
Tahsin Erdogan
72ef799b3f block: do not merge requests without consulting with io scheduler
Before merging a bio into an existing request, io scheduler is called to
get its approval first. However, the requests that come from a plug
flush may get merged by block layer without consulting with io
scheduler.

In case of CFQ, this can cause fairness problems. For instance, if a
request gets merged into a low weight cgroup's request, high weight cgroup
now will depend on low weight cgroup to get scheduled. If high weigt cgroup
needs that io request to complete before submitting more requests, then it
will also lose its timeslice.

Following script demonstrates the problem. Group g1 has a low weight, g2
and g3 have equal high weights but g2's requests are adjacent to g1's
requests so they are subject to merging. Due to these merges, g2 gets
poor disk time allocation.

cat > cfq-merge-repro.sh << "EOF"
#!/bin/bash
set -e

IO_ROOT=/mnt-cgroup/io

mkdir -p $IO_ROOT

if ! mount | grep -qw $IO_ROOT; then
  mount -t cgroup none -oblkio $IO_ROOT
fi

cd $IO_ROOT

for i in g1 g2 g3; do
  if [ -d $i ]; then
    rmdir $i
  fi
done

mkdir g1 && echo 10 > g1/blkio.weight
mkdir g2 && echo 495 > g2/blkio.weight
mkdir g3 && echo 495 > g3/blkio.weight

RUNTIME=10

(echo $BASHPID > g1/cgroup.procs &&
 fio --readonly --name name1 --filename /dev/sdb \
     --rw read --size 64k --bs 64k --time_based \
     --runtime=$RUNTIME --offset=0k &> /dev/null)&

(echo $BASHPID > g2/cgroup.procs &&
 fio --readonly --name name1 --filename /dev/sdb \
     --rw read --size 64k --bs 64k --time_based \
     --runtime=$RUNTIME --offset=64k &> /dev/null)&

(echo $BASHPID > g3/cgroup.procs &&
 fio --readonly --name name1 --filename /dev/sdb \
     --rw read --size 64k --bs 64k --time_based \
     --runtime=$RUNTIME --offset=256k &> /dev/null)&

sleep $((RUNTIME+1))

for i in g1 g2 g3; do
  echo ---- $i ----
  cat $i/blkio.time
done

EOF
# ./cfq-merge-repro.sh
---- g1 ----
8:16 162
---- g2 ----
8:16 165
---- g3 ----
8:16 686

After applying the patch:

# ./cfq-merge-repro.sh
---- g1 ----
8:16 90
---- g2 ----
8:16 445
---- g3 ----
8:16 471

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-20 21:35:12 -06:00
Jan Kara
9828c2c6c1 block: Convert fifo_time from ulong to u64
Currently rq->fifo_time is unsigned long but CFQ stores nanosecond
timestamp in it which would overflow on 32-bit archs. Convert it to u64
to avoid the overflow. Since the rq->fifo_time is unioned with struct
call_single_data(), this does not change the size of struct request in
any way.

We have to slightly fixup block/deadline-iosched.c so that comparison
happens in the right types.

Fixes: 9a7f38c42c
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-28 08:21:44 -06:00
Tahsin Erdogan
e502fb8f88 deadline: remove unused struct member
commit 63de428b13 ("deadline-iosched:
allow non-sequential batching") removed last use of last_sector.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-02-01 09:09:55 -07:00
Jan Kara
8b4922d317 block: Stop abusing csd.list for fifo_time
Block layer currently abuses rq->csd.list.next for storing fifo_time.
That is a terrible hack and completely unnecessary as well. Union
achieves the same space saving in a cleaner way.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2014-02-24 14:46:32 -08:00
Joe Perches
c1b511eb21 block: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...)
Use the helper function instead of __GFP_ZERO.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-09-11 13:22:03 -06:00
Jianpeng Ma
d50235b7bc elevator: Fix a race in elevator switching
There's a race between elevator switching and normal io operation.
    Because the allocation of struct elevator_queue and struct elevator_data
    don't in a atomic operation.So there are have chance to use NULL
    ->elevator_data.
    For example:
        Thread A:                               Thread B
        blk_queu_bio                            elevator_switch
        spin_lock_irq(q->queue_block)           elevator_alloc
        elv_merge                               elevator_init_fn

    Because call elevator_alloc, it can't hold queue_lock and the
    ->elevator_data is NULL.So at the same time, threadA call elv_merge and
    nedd some info of elevator_data.So the crash happened.

    Move the elevator_alloc into func elevator_init_fn, it make the
    operations in a atomic operation.

    Using the follow method can easy reproduce this bug
    1:dd if=/dev/sdb of=/dev/null
    2:while true;do echo noop > scheduler;echo deadline > scheduler;done

    The test method also use this method.

Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-07-03 13:25:24 +02:00
Kent Overstreet
f73a1c7d11 block: Add bio_end_sector()
Just a little convenience macro - main reason to add it now is preparing
for immutable bio vecs, it'll reduce the size of the patch that puts
bi_sector/bi_size/bi_idx into a struct bvec_iter.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Lars Ellenberg <drbd-dev@lists.linbit.com>
CC: Jiri Kosina <jkosina@suse.cz>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Neil Brown <neilb@suse.de>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: linux-s390@vger.kernel.org
CC: Chris Mason <chris.mason@fusionio.com>
CC: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
2013-03-23 14:15:29 -07:00
xiaobing tu
75274551c8 deadline: Allow 0ms deadline latency, increase the read speed
Change a timer compare from after to after-equals, thus allowing
0 timeout and making deadline schedule FIFO.

Signed-off-by: xiaobing tu <xiaobing.tu@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-12-09 19:19:23 +01:00
Tejun Heo
b2fab5acd2 elevator: make elevator_init_fn() return 0/-errno
elevator_ops->elevator_init_fn() has a weird return value.  It returns
a void * which the caller should assign to q->elevator->elevator_data
and %NULL return denotes init failure.

Update such that it returns integer 0/-errno and sets elevator_data
directly as necessary.

This makes the interface more conventional and eases further cleanup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06 21:27:21 +01:00
Tejun Heo
3d3c2379fe block, cfq: move icq cache management to block core
Let elevators set ->icq_size and ->icq_align in elevator_type and
elv_register() and elv_unregister() respectively create and destroy
kmem_cache for icq.

* elv_register() now can return failure.  All callers updated.

* icq caches are automatically named "ELVNAME_io_cq".

* cfq_slab_setup/kill() are collapsed into cfq_init/exit().

* While at it, minor indentation change for iosched_cfq.elevator_name
  for consistency.

This will help moving icq management to block core.  This doesn't
introduce any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-12-14 00:33:42 +01:00
Jeff Moyer
796d5116c4 iosched: prevent aliased requests from starving other I/O
Hi, Jens,

If you recall, I posted an RFC patch for this back in July of last year:
http://lkml.org/lkml/2010/7/13/279

The basic problem is that a process can issue a never-ending stream of
async direct I/Os to the same sector on a device, thus starving out
other I/O in the system (due to the way the alias handling works in both
cfq and deadline).  The solution I proposed back then was to start
dispatching from the fifo after a certain number of aliases had been
dispatched.  Vivek asked why we had to treat aliases differently at all,
and I never had a good answer.  So, I put together a simple patch which
allows aliases to be added to the rb tree (it adds them to the right,
though that doesn't matter as the order isn't guaranteed anyway).  I
think this is the preferred solution, as it doesn't break up time slices
in CFQ or batches in deadline.  I've tested it, and it does solve the
starvation issue.  Let me know what you think.

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-06-02 21:19:05 +02:00
Jens Axboe
7eaceaccab block: remove per-queue plugging
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 <jaxboe@fusionio.com>
2011-03-10 08:52:07 +01:00
Tejun Heo
83096ebf12 block: convert to pos and nr_sectors accessors
With recent cleanups, there is no place where low level driver
directly manipulates request fields.  This means that the 'hard'
request fields always equal the !hard fields.  Convert all
rq->sectors, nr_sectors and current_nr_sectors references to
accessors.

While at it, drop superflous blk_rq_pos() < 0 test in swim.c.

[ Impact: use pos and nr_sectors accessors ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Tested-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Mike Miller <mike.miller@hp.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Eric Moore <Eric.Moore@lsi.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Clements <paul.clements@steeleye.com>
Cc: Tim Waugh <tim@cyberelk.net>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Dario Ballabio <ballabio_dario@emc.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: unsik Kim <donari75@gmail.com>
Cc: Laurent Vivier <Laurent@lvivier.info>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-05-11 09:50:54 +02:00
Jens Axboe
b374d18a4b block: get rid of elevator_t typedef
Just use struct elevator_queue everywhere instead.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-12-29 08:29:50 +01:00
Aaron Carroll
4fb72f7646 deadline-iosched: non-functional fixes
* convert goto to simpler while loop;
 * use rq_end_sector() instead of computing manually;
 * fix false comments;
 * remove spurious whitespace;
 * convert rq_rb_root macro to an inline function.

Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:03 +02:00
Aaron Carroll
63de428b13 deadline-iosched: allow non-sequential batching
Deadline currently only batches sector-contiguous requests, so except
for a few circumstances (e.g. requests in a single direction), it is
essentially first come first served.  This is bad for throughput, so
change it to CSCAN, which means requests in a batch do not need to be
sequential and are issued in increasing sector order.

Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-09 08:56:02 +02:00
Adrian Bunk
2fdd82bd88 block: let elv_register() return void
elv_register() always returns 0, and there isn't anything it does where
it should return an error (the only error condition is so grave that
it's handled with a BUG_ON).

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-12-18 08:29:28 +01:00
Aaron Carroll
6f5d8aa638 Deadline iosched: Fix batching fairness
After switching data directions, deadline always starts the next batch
from the lowest-sector request.  This gives excessive deadline expiries
and large latency and throughput disparity between high- and low-sector
requests; an order of magnitude in some tests.

This patch changes the batching behaviour so new batches start from the
request whose expiry is earliest.

Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-11-02 08:47:25 +01:00
Aaron Carroll
dfb3d72a9a Deadline iosched: Reset batch for ordered requests
The deadline I/O scheduler does not reset the batch count when starting
a new batch at a higher-sectored request.  This means the second and
subsequent batch in the same data direction will never exceed a single
request in size whenever higher-sectored requests are pending.

This patch gives new batches in the same data direction as old ones
their full quota of requests by resetting the batch count.

Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-11-02 08:47:25 +01:00
Aaron Carroll
5d1a536621 Deadline iosched: Factor out finding latter reques
Factor finding the next request in sector-sorted order into
a function deadline_latter_request.

Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-11-02 08:47:25 +01:00
Jens Axboe
165125e1e4 [BLOCK] Get rid of request_queue_t typedef
Some of the code has been gradually transitioned to using the proper
struct request_queue, but there's lots left. So do a full sweet of
the kernel and get rid of this typedef and replace its uses with
the proper type.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-07-24 09:28:11 +02:00
Christoph Lameter
94f6030ca7 Slab allocators: Replace explicit zeroing with __GFP_ZERO
kmalloc_node() and kmem_cache_alloc_node() were not available in a zeroing
variant in the past.  But with __GFP_ZERO it is possible now to do zeroing
while allocating.

Use __GFP_ZERO to remove the explicit clearing of memory via memset whereever
we can.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:02 -07:00
Jens Axboe
bb37b94c68 [BLOCK] Cleanup unused variable passing
- ->init_queue() does not need the elevator passed in
- ->put_request() is a hot path and need not have the queue passed in
- cfq_update_io_seektime() does not need cfqd passed in

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2006-12-01 10:42:33 +01:00
Jens Axboe
0fe2347957 [PATCH] Update axboe@suse.de email address
As people often look for the copyright in files to see who to mail,
update the link to a neutral one.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 20:52:34 +02:00
Jens Axboe
8840faa1ee [PATCH] deadline-iosched: remove elevator private drq request type
A big win, we now save an allocation/free on each request! With the
previous rb/hash abstractions, we can just reuse queuelist/donelist
for the FIFO data and be done with it.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-09-30 20:27:00 +02:00
Jens Axboe
b8aca35af5 [PATCH] deadline-iosched: migrate to using the elevator rb functions
This removes the rbtree handling from deadline.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-09-30 20:26:58 +02:00
Jens Axboe
9817064b68 [PATCH] elevator: move the backmerging logic into the elevator core
Right now, every IO scheduler implements its own backmerging (except for
noop, which does no merging). That results in duplicated code for
essentially the same operation, which is never a good thing. This patch
moves the backmerging out of the io schedulers and into the elevator
core. We save 1.6kb of text and as a bonus get backmerging for noop as
well. Win-win!

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-09-30 20:26:56 +02:00
Jörn Engel
6ab3d5624e Remove obsolete #include <linux/config.h>
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-30 19:25:36 +02:00
Jens Axboe
dd67d05152 [PATCH] rbtree: support functions used by the io schedulers
They all duplicate macros to check for empty root and/or node, and
clearing a node. So put those in rbtree.h.

Signed-off-by: Jens Axboe <axboe@suse.de>
2006-06-23 17:10:39 +02:00
Akinobu Mita
bae386f788 [PATCH] iosched: use hlist for request hashtable
Use hlist instead of list_head for request hashtable in deadline-iosched
and as-iosched. It also can remove the flag to know hashed or unhashed.

Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Jens Axboe <axboe@suse.de>

 block/as-iosched.c       |   45 +++++++++++++++++++--------------------------
 block/deadline-iosched.c |   39 ++++++++++++++++-----------------------
 2 files changed, 35 insertions(+), 49 deletions(-)
2006-06-23 17:10:38 +02:00
Linus Torvalds
2edc322d42 Merge git://git.infradead.org/~dwmw2/rbtree-2.6
* git://git.infradead.org/~dwmw2/rbtree-2.6:
  [RBTREE] Switch rb_colour() et al to en_US spelling of 'color' for consistency
  Update UML kernel/physmem.c to use rb_parent() accessor macro
  [RBTREE] Update hrtimers to use rb_parent() accessor macro.
  [RBTREE] Add explicit alignment to sizeof(long) for struct rb_node.
  [RBTREE] Merge colour and parent fields of struct rb_node.
  [RBTREE] Remove dead code in rb_erase()
  [RBTREE] Update JFFS2 to use rb_parent() accessor macro.
  [RBTREE] Update eventpoll.c to use rb_parent() accessor macro.
  [RBTREE] Update key.c to use rb_parent() accessor macro.
  [RBTREE] Update ext3 to use rb_parent() accessor macro.
  [RBTREE] Change rbtree off-tree marking in I/O schedulers.
  [RBTREE] Add accessor macros for colour and parent fields of rb_node
2006-06-20 14:51:22 -07:00
Jens Axboe
bc1c116974 [PATCH] elevator switching race
There's a race between shutting down one io scheduler and firing up the
next, in which a new io could enter and cause the io scheduler to be
invoked with bad or NULL data.

To fix this, we need to maintain the queue lock for a bit longer.
Unfortunately we cannot do that, since the elevator init requires to be
run without the lock held.  This isn't easily fixable, without also
changing the mempool API.  So split the initialization into two parts,
and alloc-init operation and an attach operation.  Then we can
preallocate the io scheduler and related structures, and run the attach
inside the lock after we detach the old one.

This patch has survived 30 minutes of 1 second io scheduler switching
with a very busy io load.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-08 15:14:23 -07:00
David Woodhouse
3db3a44530 [RBTREE] Change rbtree off-tree marking in I/O schedulers.
They were abusing the rb_color field to mark nodes which weren't currently
on the tree. Fix that to use the same method as eventpoll did -- setting
the parent pointer to point back to itself. And use the appropriate
accessor macros for setting and reading the parent.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-04-21 13:15:17 +01:00
Al Viro
e572ec7e4e [PATCH] fix rmmod problems with elevator attributes, clean them up 2006-03-18 22:27:18 -05:00
Al Viro
3d1ab40f4c [PATCH] elevator_t lifetime rules and sysfs fixes 2006-03-18 18:35:43 -05:00
Arjan van de Ven
64100099ed [BLOCK] mark some block/ variables cons
the patch below marks various read-only variables in block/* as const,
so that gcc can optimize the use of them; eg gcc will replace the use by
the value directly now and will even remove the memory usage of these.

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Jens Axboe <axboe@suse.de>
2006-01-06 09:46:02 +01:00
Coywolf Qi Hunt
eb97b73d75 [BLOCK] new block/ directory comment tidy
Some leftover comments referring to drivers/block that are now block/.
They don't add any information we don't already have, so kill them.

Signed-off-by: Coywolf Qi Hunt <qiyong@fc-cn.com>
Signed-off-by: Jens Axboe <axboe@suse.de>
2005-11-18 21:59:31 +01:00
Jens Axboe
3a65dfe8c0 [BLOCK] Move all core block layer code to new block/ directory
drivers/block/ is right now a mix of core and driver parts. Lets move
the core parts to a new top level directory. Al will move the fs/
related block parts to block/ next.

Signed-off-by: Jens Axboe <axboe@suse.de>
2005-11-04 08:43:35 +01:00