scsi: megaraid_sas: Selectively apply stream detection based on IO type

Performance improvement:

Current driver calls stream detection unconditionally for all IOs.
Stream Detection logic is not required for most of the fast path IO. To
improve performance, avoid stream detection logic and do it only if
required.

Below are the cases where stream detection is required in driver:

1. All non-FastPath IOs (IOs going to FW)
2. Fast Path reads sent to ReadAhead capable VDs.

Signed-off-by: Sumit Saxena <[email protected]>
Signed-off-by: Shivasharan S <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 74dadd052be4d0567e4820370be121b0558c5b0c..ef36f2ac7cb64bc7a6affc5f8d193b3a99080049 100644 (file)
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -2664,16 +2664,6 @@ megasas_build_ldio_fusion(struct megasas_instance *instance,
        praid_context = &io_request->RaidContext;
 
        if (instance->adapter_type == VENTURA_SERIES) {
-               spin_lock_irqsave(&instance->stream_lock, spinlock_flags);
-               megasas_stream_detect(instance, cmd, &io_info);
-               spin_unlock_irqrestore(&instance->stream_lock, spinlock_flags);
-               /* In ventura if stream detected for a read and it is read ahead
-                *  capable make this IO as LDIO
-                */
-               if (is_stream_detected(&io_request->RaidContext.raid_context_g35) &&
-                   io_info.isRead && io_info.ra_capable)
-                       fp_possible = false;
-
                /* FP for Optimal raid level 1.
                 * All large RAID-1 writes (> 32 KiB, both WT and WB modes)
                 * are built by the driver as LD I/Os.
@@ -2699,6 +2689,20 @@ megasas_build_ldio_fusion(struct megasas_instance *instance,
                        }
                }
 
+               if (!fp_possible ||
+                   (io_info.isRead && io_info.ra_capable)) {
+                       spin_lock_irqsave(&instance->stream_lock,
+                                         spinlock_flags);
+                       megasas_stream_detect(instance, cmd, &io_info);
+                       spin_unlock_irqrestore(&instance->stream_lock,
+                                              spinlock_flags);
+                       /* In ventura if stream detected for a read and it is
+                        * read ahead capable make this IO as LDIO
+                        */
+                       if (is_stream_detected(&io_request->RaidContext.raid_context_g35))
+                               fp_possible = false;
+               }
+
                /* If raid is NULL, set CPU affinity to default CPU0 */
                if (raid)
                        megasas_set_raidflag_cpu_affinity(praid_context,