Commit aeb6fafb authored by Jens Axboe's avatar Jens Axboe Committed by Linus Torvalds

block: Add flag for telling the IO schedulers NOT to anticipate more IO

By default, CFQ will anticipate more IO from a given io context if the
previously completed IO was sync. This used to be fine, since the only
sync IO was reads and O_DIRECT writes. But with more "normal" sync writes
being used now, we don't want to anticipate for those.

Add a bio/request flag that informs the IO scheduler that this is a sync
request that we should not idle for. Introduce WRITE_ODIRECT specifically
for O_DIRECT writes, and make sure that the other sync writes set this
flag.
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 644b2d99
......@@ -1128,6 +1128,8 @@ void init_request_from_bio(struct request *req, struct bio *bio)
req->cmd_flags |= REQ_UNPLUG;
if (bio_rw_meta(bio))
req->cmd_flags |= REQ_RW_META;
if (bio_noidle(bio))
req->cmd_flags |= REQ_NOIDLE;
req->errors = 0;
req->hard_sector = req->sector = bio->bi_sector;
......
......@@ -1992,8 +1992,10 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
}
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
cfq_slice_expired(cfqd, 1);
else if (sync && RB_EMPTY_ROOT(&cfqq->sort_list))
else if (sync && !rq_noidle(rq) &&
RB_EMPTY_ROOT(&cfqq->sort_list)) {
cfq_arm_slice_timer(cfqd);
}
}
if (!cfqd->rq_in_driver)
......
......@@ -1126,7 +1126,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
int acquire_i_mutex = 0;
if (rw & WRITE)
rw = WRITE_SYNC;
rw = WRITE_ODIRECT;
if (bdev)
bdev_blkbits = blksize_bits(bdev_hardsect_size(bdev));
......
......@@ -145,20 +145,21 @@ struct bio {
* bit 2 -- barrier
* Insert a serialization point in the IO queue, forcing previously
* submitted IO to be completed before this one is issued.
* bit 3 -- synchronous I/O hint: the block layer will unplug immediately
* Note that this does NOT indicate that the IO itself is sync, just
* that the block layer will not postpone issue of this IO by plugging.
* bit 4 -- metadata request
* bit 3 -- synchronous I/O hint.
* bit 4 -- Unplug the device immediately after submitting this bio.
* bit 5 -- metadata request
* Used for tracing to differentiate metadata and data IO. May also
* get some preferential treatment in the IO scheduler
* bit 5 -- discard sectors
* bit 6 -- discard sectors
* Informs the lower level device that this range of sectors is no longer
* used by the file system and may thus be freed by the device. Used
* for flash based storage.
* bit 6 -- fail fast device errors
* bit 7 -- fail fast transport errors
* bit 8 -- fail fast driver errors
* bit 7 -- fail fast device errors
* bit 8 -- fail fast transport errors
* bit 9 -- fail fast driver errors
* Don't want driver retries for any fast fail whatever the reason.
* bit 10 -- Tell the IO scheduler not to wait for more requests after this
one has been submitted, even if it is a SYNC request.
*/
#define BIO_RW 0 /* Must match RW in req flags (blkdev.h) */
#define BIO_RW_AHEAD 1 /* Must match FAILFAST in req flags */
......@@ -170,6 +171,7 @@ struct bio {
#define BIO_RW_FAILFAST_DEV 7
#define BIO_RW_FAILFAST_TRANSPORT 8
#define BIO_RW_FAILFAST_DRIVER 9
#define BIO_RW_NOIDLE 10
#define bio_rw_flagged(bio, flag) ((bio)->bi_rw & (1 << (flag)))
......@@ -188,6 +190,7 @@ struct bio {
#define bio_rw_ahead(bio) bio_rw_flagged(bio, BIO_RW_AHEAD)
#define bio_rw_meta(bio) bio_rw_flagged(bio, BIO_RW_META)
#define bio_discard(bio) bio_rw_flagged(bio, BIO_RW_DISCARD)
#define bio_noidle(bio) bio_rw_flagged(bio, BIO_RW_NOIDLE)
/*
* upper 16 bits of bi_rw define the io priority of this bio
......
......@@ -118,6 +118,7 @@ enum rq_flag_bits {
__REQ_COPY_USER, /* contains copies of user pages */
__REQ_INTEGRITY, /* integrity metadata has been remapped */
__REQ_UNPLUG, /* unplug queue on submission */
__REQ_NOIDLE, /* Don't anticipate more IO after this one */
__REQ_NR_BITS, /* stops here */
};
......@@ -145,6 +146,7 @@ enum rq_flag_bits {
#define REQ_COPY_USER (1 << __REQ_COPY_USER)
#define REQ_INTEGRITY (1 << __REQ_INTEGRITY)
#define REQ_UNPLUG (1 << __REQ_UNPLUG)
#define REQ_NOIDLE (1 << __REQ_NOIDLE)
#define BLK_MAX_CDB 16
......@@ -633,6 +635,7 @@ static inline bool rq_is_sync(struct request *rq)
}
#define rq_is_meta(rq) ((rq)->cmd_flags & REQ_RW_META)
#define rq_noidle(rq) ((rq)->cmd_flags & REQ_NOIDLE)
static inline int blk_queue_full(struct request_queue *q, int sync)
{
......
......@@ -95,11 +95,12 @@ struct inodes_stat_t {
#define SWRITE 3 /* for ll_rw_block() - wait for buffer lock */
#define READ_SYNC (READ | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
#define READ_META (READ | (1 << BIO_RW_META))
#define WRITE_SYNC (WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
#define WRITE_SYNC_PLUG (WRITE | (1 << BIO_RW_SYNCIO))
#define SWRITE_SYNC (SWRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
#define WRITE_SYNC_PLUG (WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))
#define WRITE_SYNC (WRITE_SYNC_PLUG | (1 << BIO_RW_UNPLUG))
#define WRITE_ODIRECT (WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
#define SWRITE_SYNC_PLUG \
(SWRITE | (1 << BIO_RW_SYNCIO))
(SWRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_NOIDLE))
#define SWRITE_SYNC (SWRITE_SYNC_PLUG | (1 << BIO_RW_UNPLUG))
#define WRITE_BARRIER (WRITE | (1 << BIO_RW_BARRIER))
#define DISCARD_NOBARRIER (1 << BIO_RW_DISCARD)
#define DISCARD_BARRIER ((1 << BIO_RW_DISCARD) | (1 << BIO_RW_BARRIER))
......
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