scsi: mpi3mr: A performance fix

Commit 0c52310f2600 ("hrtimer: Ignore slack time for RT tasks in
schedule_hrtimeout_range()") effectivelly shortens a sleep in a polling
function in the driver.  That is causing a performance regression as the
new value of just 2us is too low, in certain tests the perf drop is ~30%.
Fix this by adjusting the sleep to 20us (close to the previous value).

Reported-by: Jan Jurca <jjurca@redhat.com>
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Sumit Saxena <sumit.saxena@broadcom.com>
Link: https://lore.kernel.org/r/20240903144729.37218-1-thenzl@redhat.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/mpi3mr/mpi3mr.h b/drivers/scsi/mpi3mr/mpi3mr.h
index 1dc640d..0f9101a 100644 (file)
--- a/drivers/scsi/mpi3mr/mpi3mr.h
+++ b/drivers/scsi/mpi3mr/mpi3mr.h
@@ -178,7 +178,7 @@ extern atomic64_t event_counter;
 #define MPI3MR_DEFAULT_SDEV_QD 32
 
 /* Definitions for Threaded IRQ poll*/
-#define MPI3MR_IRQ_POLL_SLEEP                  2
+#define MPI3MR_IRQ_POLL_SLEEP                  20
 #define MPI3MR_IRQ_POLL_TRIGGER_IOCOUNT                8
 
 /* Definitions for the controller security status*/

diff --git a/drivers/scsi/mpi3mr/mpi3mr_fw.c b/drivers/scsi/mpi3mr/mpi3mr_fw.c
index 2e1a92d..35ca54b 100644 (file)
--- a/drivers/scsi/mpi3mr/mpi3mr_fw.c
+++ b/drivers/scsi/mpi3mr/mpi3mr_fw.c
@@ -728,7 +728,7 @@ static irqreturn_t mpi3mr_isr_poll(int irq, void *privdata)
                            mpi3mr_process_op_reply_q(mrioc,
                                intr_info->op_reply_q);
 
-               usleep_range(MPI3MR_IRQ_POLL_SLEEP, 10 * MPI3MR_IRQ_POLL_SLEEP);
+               usleep_range(MPI3MR_IRQ_POLL_SLEEP, MPI3MR_IRQ_POLL_SLEEP + 1);
 
        } while (atomic_read(&intr_info->op_reply_q->pend_ios) &&
            (num_op_reply < mrioc->max_host_ios));