From 41e05a12c7aae16f0381103af3e5ca791e87ce59 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Tue, 18 Aug 2009 15:43:32 +0200 Subject: [PATCH] [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 Signed-off-by: Christof Schmitt Signed-off-by: James Bottomley --- drivers/s390/scsi/zfcp_def.h | 2 +- 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 { struct zfcp_qdio_queue req_q; spinlock_t stat_lock; spinlock_t req_q_lock; - ktime_t req_q_time; + unsigned long long req_q_time; u64 req_q_util; atomic_t req_q_full; 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) } /* this needs to be called prior to updating the queue fill level */ -static void zfcp_qdio_account(struct zfcp_qdio *qdio) +static inline void zfcp_qdio_account(struct zfcp_qdio *qdio) { - ktime_t now; - s64 span; + unsigned long long now, span; int free, used; spin_lock(&qdio->stat_lock); - now = ktime_get(); - span = ktime_us_delta(now, qdio->req_q_time); - free = max(0, atomic_read(&qdio->req_q.count)); + now = get_clock_monotonic(); + span = (now - qdio->req_q_time) >> 12; + free = atomic_read(&qdio->req_q.count); used = QDIO_MAX_BUFFERS_PER_Q - free; qdio->req_q_util += used * span; qdio->req_q_time = now; -- GitLab