RE: [PATCH V4 12/12] scsi: replace sdev->device_busy with sbitmap

Kashyap Desai
2020-11-19T07:09:07Z

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> > /**
> > * megasas_get_cmd_fusion - Get a command from the free pool
> > * @instance: Adapter soft state
> > @@ -359,10 +385,7 @@ megasas_get_msix_index(struct megasas_instance
> > *instance, {
> > int sdev_busy;
> >
> > - /* TBD - if sml remove device_busy in future, driver
> > - * should track counter in internal structure.
> > - */
> > - sdev_busy = atomic_read(&scmd->device->device_busy);
> > + sdev_busy = megasas_sdev_busy_read(scmd);
>
> The above is only used for MR_BALANCED_PERF_MODE, so maybe you can
> skip inc/dec/read the counter for other perf mode.

Agree. I have created V2.

Subject: [PATCH] megaraid_sas: v2 replace sdev_busy with local counter

use local tracking of per sdev outstanding command since sdev_busy in
SML is improved for peformance reason using sbitmap (earlier it was
atomic variable).

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
---
drivers/scsi/megaraid/megaraid_sas.h | 2 +
drivers/scsi/megaraid/megaraid_sas_fusion.c | 51 +++++++++++++++++----
2 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas.h
b/drivers/scsi/megaraid/megaraid_sas.h
index 0f808d63580e..0c6a56b24c6e 100644
--- a/drivers/scsi/megaraid/megaraid_sas.h
+++ b/drivers/scsi/megaraid/megaraid_sas.h
@@ -2019,10 +2019,12 @@ union megasas_frame {
* struct MR_PRIV_DEVICE - sdev private hostdata
* @is_tm_capable: firmware managed tm_capable flag
* @tm_busy: TM request is in progress
+ * @sdev_priv_busy: pending command per sdev
*/
struct MR_PRIV_DEVICE {
bool is_tm_capable;
bool tm_busy;
+ atomic_t sdev_priv_busy;
atomic_t r1_ldio_hint;
u8 interface_type;
u8 task_abort_tmo;
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c
b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index fd607287608e..c630404cbb2d 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -220,6 +220,44 @@ megasas_clear_intr_fusion(struct megasas_instance
*instance)
return 1;
}

+static inline void
+megasas_sdev_busy_inc(struct megasas_instance *instance,
+ struct scsi_cmnd *scmd)
+{
+ struct MR_PRIV_DEVICE *mr_device_priv_data;
+
+ if (instance->perf_mode != MR_BALANCED_PERF_MODE)
+ return;
+
+ mr_device_priv_data = scmd->device->hostdata;
+ atomic_inc(&mr_device_priv_data->sdev_priv_busy);
+}
+static inline void
+megasas_sdev_busy_dec(struct megasas_instance *instance,
+ struct scsi_cmnd *scmd)
+{
+ struct MR_PRIV_DEVICE *mr_device_priv_data;
+
+ if (instance->perf_mode != MR_BALANCED_PERF_MODE)
+ return;
+
+ mr_device_priv_data = scmd->device->hostdata;
+ atomic_dec(&mr_device_priv_data->sdev_priv_busy);
+}
+static inline int
+megasas_sdev_busy_read(struct megasas_instance *instance,
+ struct scsi_cmnd *scmd)
+{
+ struct MR_PRIV_DEVICE *mr_device_priv_data;
+
+ if (instance->perf_mode != MR_BALANCED_PERF_MODE)
+ return 0;
+
+ mr_device_priv_data = scmd->device->hostdata;
+ return atomic_read(&mr_device_priv_data->sdev_priv_busy);
+}
+
+
/**
* megasas_get_cmd_fusion - Get a command from the free pool
* @instance: Adapter soft state
@@ -357,15 +395,9 @@ megasas_get_msix_index(struct megasas_instance
*instance,
struct megasas_cmd_fusion *cmd,
u8 data_arms)
{
- int sdev_busy;
-
- /* TBD - if sml remove device_busy in future, driver
- * should track counter in internal structure.
- */
- sdev_busy = atomic_read(&scmd->device->device_busy);
-
if (instance->perf_mode == MR_BALANCED_PERF_MODE &&
- sdev_busy > (data_arms * MR_DEVICE_HIGH_IOPS_DEPTH)) {
+ (megasas_sdev_busy_read(instance, scmd) >
+ (data_arms * MR_DEVICE_HIGH_IOPS_DEPTH))) {
cmd->request_desc->SCSIIO.MSIxIndex =
mega_mod64((atomic64_add_return(1,
&instance->high_iops_outstanding) /
MR_HIGH_IOPS_BATCH_COUNT),
instance->low_latency_index_start);
@@ -3390,6 +3422,7 @@ megasas_build_and_issue_cmd_fusion(struct
megasas_instance *instance,
* Issue the command to the FW
*/

+ megasas_sdev_busy_inc(instance, scmd);
megasas_fire_cmd_fusion(instance, req_desc);

if (r1_cmd)
@@ -3450,6 +3483,7 @@ megasas_complete_r1_command(struct megasas_instance
*instance,
scmd_local->SCp.ptr = NULL;
megasas_return_cmd_fusion(instance, cmd);
scsi_dma_unmap(scmd_local);
+ megasas_sdev_busy_dec(instance, scmd_local);
scmd_local->scsi_done(scmd_local);
}
}
@@ -3550,6 +3584,7 @@ complete_cmd_fusion(struct megasas_instance
*instance, u32 MSIxIndex,
scmd_local->SCp.ptr = NULL;
megasas_return_cmd_fusion(instance,
cmd_fusion);
scsi_dma_unmap(scmd_local);
+ megasas_sdev_busy_dec(instance,
scmd_local);
scmd_local->scsi_done(scmd_local);
} else /* Optimal VD - R1 FP command completion.
*/
megasas_complete_r1_command(instance,
cmd_fusion);
--
>
>
>
> Thanks,
> Ming

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