linux-toradex.git/block/bfq-wf2q.c, branch v5.6-rc5

block, bfq: get a ref to a group when adding it to a service tree

2020-02-03T13:58:15+00:00

BFQ schedules generic entities, which may represent either bfq_queues
or groups of bfq_queues. When an entity is inserted into a service
tree, a reference must be taken, to make sure that the entity does not
disappear while still referred in the tree. Unfortunately, such a
reference is mistakenly taken only if the entity represents a
bfq_queue. This commit takes a reference also in case the entity
represents a group.

Tested-by: Oleksandr Natalenko 
Tested-by: Chris Evich 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: extend incomplete name of field on_st

2020-02-03T13:58:15+00:00

The flag on_st in the bfq_entity data structure is true if the entity
is on a service tree or is in service. Yet the name of the field,
confusingly, does not mention the second, very important case. Extend
the name to mention the second case too.

Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: improve arithmetic division in bfq_delta()

2020-01-22T17:34:11+00:00

do_div() does a 64-by-32 division. Use div64_ul() instead of it
if the divisor is unsigned long, to avoid truncation to 32-bit.
And as a nice side effect also cleans up the function a bit.

Signed-off-by: Wen Yang 
Cc: Paolo Valente 
Cc: Jens Axboe 
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jens Axboe

bfq: Fix the missing barrier in __bfq_entity_update_weight_prio

2019-09-06T20:33:48+00:00

The comment of bfq_group_set_weight says the reading of prio_changed
should happen before the reading of weight, but a memory barrier is
missing here. Add it now, to match the smp_wmb() there.

Signed-off-by: Fam Zheng 
Reviewed-by: Paolo Valente 
Signed-off-by: Jens Axboe

block: switch all files cleared marked as GPLv2 or later to SPDX tags

2019-04-30T22:11:59+00:00

All these files have some form of the usual GPLv2 or later boilerplate.
Switch them to use SPDX tags instead.

Reviewed-by: Chaitanya Kulkarni 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

Merge tag 'v5.1-rc6' into for-5.2/block

2019-04-22T15:47:36+00:00

Pull in v5.1-rc6 to resolve two conflicts. One is in BFQ, in just a
comment, and is trivial. The other one is a conflict due to a later fix
in the bio multi-page work, and needs a bit more care.

* tag 'v5.1-rc6': (770 commits)
  Linux 5.1-rc6
  block: make sure that bvec length can't be overflow
  block: kill all_q_node in request_queue
  x86/cpu/intel: Lower the "ENERGY_PERF_BIAS: Set to normal" message's log priority
  coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping
  mm/kmemleak.c: fix unused-function warning
  init: initialize jump labels before command line option parsing
  kernel/watchdog_hld.c: hard lockup message should end with a newline
  kcov: improve CONFIG_ARCH_HAS_KCOV help text
  mm: fix inactive list balancing between NUMA nodes and cgroups
  mm/hotplug: treat CMA pages as unmovable
  proc: fixup proc-pid-vm test
  proc: fix map_files test on F29
  mm/vmstat.c: fix /proc/vmstat format for CONFIG_DEBUG_TLBFLUSH=y CONFIG_SMP=n
  mm/memory_hotplug: do not unlock after failing to take the device_hotplug_lock
  mm: swapoff: shmem_unuse() stop eviction without igrab()
  mm: swapoff: take notice of completion sooner
  mm: swapoff: remove too limiting SWAP_UNUSE_MAX_TRIES
  mm: swapoff: shmem_find_swap_entries() filter out other types
  slab: store tagged freelist for off-slab slabmgmt
  ...

Signed-off-by: Jens Axboe

block, bfq: fix use after free in bfq_bfqq_expire

2019-04-10T13:54:38+00:00

The function bfq_bfqq_expire() invokes the function
__bfq_bfqq_expire(), and the latter may free the in-service bfq-queue.
If this happens, then no other instruction of bfq_bfqq_expire() must
be executed, or a use-after-free will occur.

Basing on the assumption that __bfq_bfqq_expire() invokes
bfq_put_queue() on the in-service bfq-queue exactly once, the queue is
assumed to be freed if its refcounter is equal to one right before
invoking __bfq_bfqq_expire().

But, since commit 9dee8b3b057e ("block, bfq: fix queue removal from
weights tree") this assumption is false. __bfq_bfqq_expire() may also
invoke bfq_weights_tree_remove() and, since commit 9dee8b3b057e
("block, bfq: fix queue removal from weights tree"), also
the latter function may invoke bfq_put_queue(). So __bfq_bfqq_expire()
may invoke bfq_put_queue() twice, and this is the actual case where
the in-service queue may happen to be freed.

To address this issue, this commit moves the check on the refcounter
of the queue right around the last bfq_put_queue() that may be invoked
on the queue.

Fixes: 9dee8b3b057e ("block, bfq: fix queue removal from weights tree")
Reported-by: Dmitrii Tcvetkov 
Reported-by: Douglas Anderson 
Tested-by: Dmitrii Tcvetkov 
Tested-by: Douglas Anderson 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: fix some typos in comments

2019-04-08T16:05:43+00:00

Some of the comments in the bfq files had typos. This patch fixes them.

Signed-off-by: Angelo Ruocco 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block, bfq: do not idle for lowest-weight queues

2019-04-01T14:15:39+00:00

In most cases, it is detrimental for throughput to plug I/O dispatch
when the in-service bfq_queue becomes temporarily empty (plugging is
performed to wait for the possible arrival, soon, of new I/O from the
in-service queue). There is however a case where plugging is needed
for service guarantees. If a bfq_queue, say Q, has a higher weight
than some other active bfq_queue, and is sync, i.e., contains sync
I/O, then, to guarantee that Q does receive a higher share of the
throughput than other lower-weight queues, it is necessary to plug I/O
dispatch when Q remains temporarily empty while being served.

For this reason, BFQ performs I/O plugging when some active bfq_queue
has a higher weight than some other active bfq_queue. But this is
unnecessarily overkill. In fact, if the in-service bfq_queue actually
has a weight lower than or equal to the other queues, then the queue
*must not* be guaranteed a higher share of the throughput than the
other queues. So, not plugging I/O cannot cause any harm to the
queue. And can boost throughput.

Taking advantage of this fact, this commit does not plug I/O for sync
bfq_queues with a weight lower than or equal to the weights of the
other queues. Here is an example of the resulting throughput boost
with the dbench workload, which is particularly nasty for BFQ. With
the dbench test in the Phoronix suite, BFQ reaches its lowest total
throughput with 6 clients on a filesystem with journaling, in case the
journaling daemon has a higher weight than normal processes. Before
this commit, the total throughput was ~80 MB/sec on a PLEXTOR PX-256M5,
after this commit it is ~100 MB/sec.

Tested-by: Holger Hoffstätte 
Tested-by: Oleksandr Natalenko 
Signed-off-by: Paolo Valente 
Signed-off-by: Jens Axboe

block/bfq: fix ifdef for CONFIG_BFQ_GROUP_IOSCHED=y

2019-04-01T12:56:15+00:00

Replace BFQ_GROUP_IOSCHED_ENABLED with CONFIG_BFQ_GROUP_IOSCHED.
Code under these ifdefs never worked, something might be broken.

Fixes: 0471559c2fbd ("block, bfq: add/remove entity weights correctly")
Fixes: 73d58118498b ("block, bfq: consider also ioprio classes in symmetry detection")
Reviewed-by: Holger Hoffstätte 
Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Jens Axboe