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block: cleanup the memory stall accounting in submit_bio

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Instead of a convoluted chain just check for REQ_OP_READ directly,
and keep all the memory stall code together in a single unlikely
branch.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2020-04-28 13:27:54 +02:00 committed by Jens Axboe
parent 3fdd40861d
commit 760f83ea63
1 changed files with 14 additions and 16 deletions
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30
block/blk-core.c
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@ -1148,10 +1148,6 @@ EXPORT_SYMBOL_GPL(direct_make_request);
*/
blk_qc_t submit_bio(struct bio *bio)
{
bool workingset_read = false;
unsigned long pflags;
blk_qc_t ret;
if (blkcg_punt_bio_submit(bio))
return BLK_QC_T_NONE;
@ -1170,8 +1166,6 @@ blk_qc_t submit_bio(struct bio *bio)
if (op_is_write(bio_op(bio))) {
count_vm_events(PGPGOUT, count);
} else {
if (bio_flagged(bio, BIO_WORKINGSET))
workingset_read = true;
task_io_account_read(bio->bi_iter.bi_size);
count_vm_events(PGPGIN, count);
}
@ -1187,20 +1181,24 @@ blk_qc_t submit_bio(struct bio *bio)
}
/*
* If we're reading data that is part of the userspace
* workingset, count submission time as memory stall. When the
* device is congested, or the submitting cgroup IO-throttled,
* submission can be a significant part of overall IO time.
* If we're reading data that is part of the userspace workingset, count
* submission time as memory stall. When the device is congested, or
* the submitting cgroup IO-throttled, submission can be a significant
* part of overall IO time.
*/
if (workingset_read)
if (unlikely(bio_op(bio) == REQ_OP_READ &&
bio_flagged(bio, BIO_WORKINGSET))) {
unsigned long pflags;
blk_qc_t ret;
psi_memstall_enter(&pflags);
ret = generic_make_request(bio);
if (workingset_read)
ret = generic_make_request(bio);
psi_memstall_leave(&pflags);
return ret;
return ret;
}
return generic_make_request(bio);
}
EXPORT_SYMBOL(submit_bio);