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author | Jens Axboe <jens.axboe@oracle.com> | 2009-04-06 14:48:07 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-06 08:04:54 -0700 |
commit | aeb6fafb8fa53266d70ca7474fcda2bdaf96524a (patch) | |
tree | ebe8e0c616a9dbfdfe5184b64d0150ea02d3d1b2 /include/linux/bio.h | |
parent | 644b2d99b7a8677a56909a7b1fde31677eba4471 (diff) | |
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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: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/bio.h')
-rw-r--r-- | include/linux/bio.h | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/include/linux/bio.h b/include/linux/bio.h index b05b1d4..b900d2c6 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -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 |