The current synchronization between lpfc_scsi_cmd_iocb_cmpl()
and lpfc_abort_handler() requires us to take two spin_locks,
which kills performance for high end setups.
Looking at it, the synchronization is done for two reasons:
- Avoiding an abort for a command which is already completed
- Waiting for the completion to finish before proceeding
However, in both cases we rely on a completion to come in
for _both_ commands, the original and the abort TMF.
So there is no need to wait for the completion of the TMF;
once the TMF is underway we will be getting a completion for
both.
So we can check if the 'abort_completions' flag is set in the
host template and do away with these synchronisation points
altogether to speed up I/O processing.
At the same time the original code is left in place so one can
select the original behaviour by simply disabling the
'abort_completions' host template flag.
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
---
drivers/scsi/lpfc/lpfc_scsi.c | 80 +++++++++++++++++++++++++------------------
1 file changed, 47 insertions(+), 33 deletions(-)
diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index fde5b00..fab387c 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -4133,23 +4133,32 @@ lpfc_scsi_cmd_iocb_cmpl(struct lpfc_hba *phba, struct lpfc_iocbq *pIocbIn,
lpfc_scsi_unprep_dma_buf(phba, lpfc_cmd);
+ /*
+ * If the 'abort_completions' flag is set we can
+ * release the scsi_buf before calling 'done', thereby
+ * avoiding a race condition between aborts and scsi_done
+ */
+ if (shost->hostt->abort_completions)
+ lpfc_release_scsi_buf(phba, lpfc_cmd);
+
/* The sdev is not guaranteed to be valid post scsi_done upcall. */
cmd->scsi_done(cmd);
- spin_lock_irqsave(&phba->hbalock, flags);
- lpfc_cmd->pCmd = NULL;
- spin_unlock_irqrestore(&phba->hbalock, flags);
-
- /*
- * If there is a thread waiting for command completion
- * wake up the thread.
- */
- spin_lock_irqsave(shost->host_lock, flags);
- if (lpfc_cmd->waitq)
- wake_up(lpfc_cmd->waitq);
- spin_unlock_irqrestore(shost->host_lock, flags);
+ if (!shost->hostt->abort_completions) {
+ spin_lock_irqsave(&phba->hbalock, flags);
+ lpfc_cmd->pCmd = NULL;
+ spin_unlock_irqrestore(&phba->hbalock, flags);
- lpfc_release_scsi_buf(phba, lpfc_cmd);
+ /*
+ * If there is a thread waiting for command completion
+ * wake up the thread.
+ */
+ spin_lock_irqsave(shost->host_lock, flags);
+ if (lpfc_cmd->waitq)
+ wake_up(lpfc_cmd->waitq);
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ lpfc_release_scsi_buf(phba, lpfc_cmd);
+ }
}
/**
@@ -4677,7 +4686,6 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
struct lpfc_sli_ring *pring_s4;
int ring_number, ret_val;
unsigned long flags, iflags;
- DECLARE_WAIT_QUEUE_HEAD_ONSTACK(waitq);
status = fc_block_scsi_eh(cmnd);
if (status != 0 && status != SUCCESS)
@@ -4690,7 +4698,7 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
lpfc_printf_vlog(vport, KERN_WARNING, LOG_FCP,
"3168 SCSI Layer abort requested I/O has been "
"flushed by LLD.\n");
- return FAILED;
+ return shost->hostt->abort_completions ? SUCCESS : FAILED;
}
lpfc_cmd = (struct lpfc_scsi_buf *)cmnd->host_scribble;
@@ -4700,7 +4708,7 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
"2873 SCSI Layer I/O Abort Request IO CMPL Status "
"x%x ID %d LUN %llu\n",
SUCCESS, cmnd->device->id, cmnd->device->lun);
- return SUCCESS;
+ return shost->hostt->abort_completions ? SUCCESS : FAILED;
}
iocb = &lpfc_cmd->cur_iocbq;
@@ -4710,7 +4718,7 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
lpfc_printf_vlog(vport, KERN_WARNING, LOG_FCP,
"3169 SCSI Layer abort requested I/O has been "
"cancelled by LLD.\n");
- return FAILED;
+ return shost->hostt->abort_completions ? SUCCESS : FAILED;
}
/*
* If pCmd field of the corresponding lpfc_scsi_buf structure
@@ -4802,24 +4810,28 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
&phba->sli.ring[LPFC_FCP_RING], HA_R0RE_REQ);
wait_for_cmpl:
- lpfc_cmd->waitq = &waitq;
- /* Wait for abort to complete */
- wait_event_timeout(waitq,
- (lpfc_cmd->pCmd != cmnd),
- msecs_to_jiffies(2*vport->cfg_devloss_tmo*1000));
+ if (!shost->hostt->abort_completions) {
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(waitq);
- spin_lock_irqsave(shost->host_lock, flags);
- lpfc_cmd->waitq = NULL;
- spin_unlock_irqrestore(shost->host_lock, flags);
+ lpfc_cmd->waitq = &waitq;
+ /* Wait for abort to complete */
+ wait_event_timeout(waitq,
+ (lpfc_cmd->pCmd != cmnd),
+ msecs_to_jiffies(2*vport->cfg_devloss_tmo*1000));
- if (lpfc_cmd->pCmd == cmnd) {
- ret = FAILED;
- lpfc_printf_vlog(vport, KERN_ERR, LOG_FCP,
- "0748 abort handler timed out waiting "
- "for abortng I/O (xri:x%x) to complete: "
- "ret %#x, ID %d, LUN %llu\n",
- iocb->sli4_xritag, ret,
- cmnd->device->id, cmnd->device->lun);
+ spin_lock_irqsave(shost->host_lock, flags);
+ lpfc_cmd->waitq = NULL;
+ spin_unlock_irqrestore(shost->host_lock, flags);
+
+ if (lpfc_cmd->pCmd == cmnd) {
+ ret = FAILED;
+ lpfc_printf_vlog(vport, KERN_ERR, LOG_FCP,
+ "0748 abort handler timed out waiting "
+ "for abortng I/O (xri:x%x) to complete: "
+ "ret %#x, ID %d, LUN %llu\n",
+ iocb->sli4_xritag, ret,
+ cmnd->device->id, cmnd->device->lun);
+ }
}
goto out;
@@ -5927,6 +5939,7 @@ struct scsi_host_template lpfc_template = {
.vendor_id = LPFC_NL_VENDOR_ID,
.change_queue_depth = scsi_change_queue_depth,
.track_queue_depth = 1,
+ .abort_completions = 1,
};
struct scsi_host_template lpfc_vport_template = {
@@ -5950,4 +5963,5 @@ struct scsi_host_template lpfc_vport_template = {
.max_sectors = 0xFFFF,
.change_queue_depth = scsi_change_queue_depth,
.track_queue_depth = 1,
+ .abort_completions = 1,
};
--
1.8.5.6
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