linux.git/block/deadline-iosched.c, branch master

block: remove legacy IO schedulers

2018-11-07T20:42:32+00:00

Retain the deadline documentation, as that carries over to mq-deadline
as well.

Tested-by: Ming Lei 
Reviewed-by: Omar Sandoval 
Signed-off-by: Jens Axboe

block drivers/block: Use octal not symbolic permissions

2018-05-24T19:38:59+00:00

Convert the S_ symbolic permissions to their octal equivalents as
using octal and not symbolic permissions is preferred by many as more
readable.

see: https://lkml.org/lkml/2016/8/2/1945

Done with automated conversion via:
$ ./scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace 

Miscellanea:

o Wrapped modified multi-line calls to a single line where appropriate
o Realign modified multi-line calls to open parenthesis

Signed-off-by: Joe Perches 
Signed-off-by: Jens Axboe

deadline-iosched: Introduce zone locking support

2018-01-05T16:22:17+00:00

Introduce zone write locking to avoid write request reordering with
zoned block devices. This is achieved using a finer selection of the
next request to dispatch:
1) Any non-write request is always allowed to proceed.
2) Any write to a conventional zone is always allowed to proceed.
3) For a write to a sequential zone, the zone lock is first checked.
   a) If the zone is not locked, the write is allowed to proceed after
      its target zone is locked.
   b) If the zone is locked, the write request is skipped and the next
      request in the dispatch queue tested (back to step 1).

For a write request that has locked its target zone, the zone is
unlocked either when the request completes and the method
deadline_request_completed() is called, or when the request is requeued
using the method deadline_add_request().

Requests targeting a locked zone are always left in the scheduler queue
to preserve the initial write order. If no write request can be
dispatched, allow reads to be dispatched even if the write batch is not
done.

If the device used is not a zoned block device, or if zoned block device
support is disabled, this patch does not modify deadline behavior.

Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Signed-off-by: Jens Axboe

deadline-iosched: Introduce dispatch helpers

2018-01-05T16:22:17+00:00

Avoid directly referencing the next_rq and fifo_list arrays using the
helper functions deadline_next_request() and deadline_fifo_request() to
facilitate changes in the dispatch request selection in
deadline_dispatch_requests() for zoned block devices.

While at it, also remove the unnecessary forward declaration of the
function deadline_move_request().

Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Signed-off-by: Jens Axboe

block, scheduler: convert xxx_var_store to void

2017-08-28T16:01:08+00:00

The last parameter "count" never be used in xxx_var_store,
convert these functions to void.

Signed-off-by: weiping zhang 
Signed-off-by: Jens Axboe

block: enumify ELEVATOR_*_MERGE

2017-02-08T20:43:06+00:00

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 
Signed-off-by: Jens Axboe

block: move existing elevator ops to union

2017-01-17T17:03:33+00:00

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 
Reviewed-by: Johannes Thumshirn 
Reviewed-by: Bart Van Assche 
Reviewed-by: Omar Sandoval

block: do not merge requests without consulting with io scheduler

2016-07-21T03:35:12+00:00

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 
Signed-off-by: Jens Axboe

block: Convert fifo_time from ulong to u64

2016-06-28T14:21:44+00:00

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: 9a7f38c42c2b92391d9dabaf9f51df7cfe5608e4
Signed-off-by: Jan Kara 
Signed-off-by: Jens Axboe

deadline: remove unused struct member

2016-02-01T16:09:55+00:00

commit 63de428b139d3d31d86ebe25ae97b33f6540fb7e ("deadline-iosched:
allow non-sequential batching") removed last use of last_sector.

Signed-off-by: Tahsin Erdogan 
Reviewed-by: Jeff Moyer 
Signed-off-by: Jens Axboe