diff options
author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2009-08-18 09:43:32 -0400 |
---|---|---|
committer | James Bottomley <James.Bottomley@suse.de> | 2009-09-05 09:49:49 -0400 |
commit | 41e05a12c7aae16f0381103af3e5ca791e87ce59 (patch) | |
tree | 3db57f11d9f2183215a52796fea113ce96b5abd8 /drivers/s390 | |
parent | b592e89ac9af521be164490e45c53c93e89c776f (diff) |
[SCSI] zfcp: optimize zfcp_qdio_account
Remove expensive ktime_get()/ktime_us_delta() functions from the hot
path and use get_clock_monotonic() instead. This elimates seven
function calls and avoids a lot of unnecessary calculations.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Diffstat (limited to 'drivers/s390')
-rw-r--r-- | drivers/s390/scsi/zfcp_def.h | 2 | ||||
-rw-r--r-- | drivers/s390/scsi/zfcp_qdio.c | 11 |
2 files changed, 6 insertions, 7 deletions
diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h index cc98eead2c3c..7da2fad8f515 100644 --- a/drivers/s390/scsi/zfcp_def.h +++ b/drivers/s390/scsi/zfcp_def.h | |||
@@ -438,7 +438,7 @@ struct zfcp_qdio { | |||
438 | struct zfcp_qdio_queue req_q; | 438 | struct zfcp_qdio_queue req_q; |
439 | spinlock_t stat_lock; | 439 | spinlock_t stat_lock; |
440 | spinlock_t req_q_lock; | 440 | spinlock_t req_q_lock; |
441 | ktime_t req_q_time; | 441 | unsigned long long req_q_time; |
442 | u64 req_q_util; | 442 | u64 req_q_util; |
443 | atomic_t req_q_full; | 443 | atomic_t req_q_full; |
444 | wait_queue_head_t req_q_wq; | 444 | wait_queue_head_t req_q_wq; |
diff --git a/drivers/s390/scsi/zfcp_qdio.c b/drivers/s390/scsi/zfcp_qdio.c index 2b499e28ff1f..6c5228b627fc 100644 --- a/drivers/s390/scsi/zfcp_qdio.c +++ b/drivers/s390/scsi/zfcp_qdio.c | |||
@@ -56,16 +56,15 @@ static void zfcp_qdio_zero_sbals(struct qdio_buffer *sbal[], int first, int cnt) | |||
56 | } | 56 | } |
57 | 57 | ||
58 | /* this needs to be called prior to updating the queue fill level */ | 58 | /* this needs to be called prior to updating the queue fill level */ |
59 | static void zfcp_qdio_account(struct zfcp_qdio *qdio) | 59 | static inline void zfcp_qdio_account(struct zfcp_qdio *qdio) |
60 | { | 60 | { |
61 | ktime_t now; | 61 | unsigned long long now, span; |
62 | s64 span; | ||
63 | int free, used; | 62 | int free, used; |
64 | 63 | ||
65 | spin_lock(&qdio->stat_lock); | 64 | spin_lock(&qdio->stat_lock); |
66 | now = ktime_get(); | 65 | now = get_clock_monotonic(); |
67 | span = ktime_us_delta(now, qdio->req_q_time); | 66 | span = (now - qdio->req_q_time) >> 12; |
68 | free = max(0, atomic_read(&qdio->req_q.count)); | 67 | free = atomic_read(&qdio->req_q.count); |
69 | used = QDIO_MAX_BUFFERS_PER_Q - free; | 68 | used = QDIO_MAX_BUFFERS_PER_Q - free; |
70 | qdio->req_q_util += used * span; | 69 | qdio->req_q_util += used * span; |
71 | qdio->req_q_time = now; | 70 | qdio->req_q_time = now; |