[PATCH V3 2/2] mmc: hsq: dynamic adjustment of hsq->depth

[Wenchao Chen]

Increasing hsq_depth improves random write performance.

Signed-off-by: Wenchao Chen <wenchao.chen@xxxxxxxxxx>
---
 drivers/mmc/host/mmc_hsq.c | 27 +++++++++++++++++++++++++++
 drivers/mmc/host/mmc_hsq.h |  5 +++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/mmc/host/mmc_hsq.c b/drivers/mmc/host/mmc_hsq.c
index 8556cacb21a1..0984c39108ba 100644
--- a/drivers/mmc/host/mmc_hsq.c
+++ b/drivers/mmc/host/mmc_hsq.c
@@ -21,6 +21,31 @@ static void mmc_hsq_retry_handler(struct work_struct *work)
 	mmc->ops->request(mmc, hsq->mrq);
 }
 
+static void mmc_hsq_modify_threshold(struct mmc_hsq *hsq)
+{
+	struct mmc_host *mmc = hsq->mmc;
+	struct mmc_request *mrq;
+	struct hsq_slot *slot;
+	int need_change = 0;
+	int tag;
+
+	for (tag = 0; tag < HSQ_NUM_SLOTS; tag++) {
+		slot = &hsq->slot[tag];
+		mrq = slot->mrq;
+		if (mrq && mrq->data &&
+			(mrq->data->blksz * mrq->data->blocks == 4096) &&
+			(mrq->data->flags & MMC_DATA_WRITE))
+			need_change++;
+		else
+			break;
+	}
+
+	if (need_change > 1)
+		mmc->hsq_depth = HSQ_PERFORMANCE_DEPTH;
+	else
+		mmc->hsq_depth = HSQ_NORMAL_DEPTH;
+}
+
 static void mmc_hsq_pump_requests(struct mmc_hsq *hsq)
 {
 	struct mmc_host *mmc = hsq->mmc;
@@ -42,6 +67,8 @@ static void mmc_hsq_pump_requests(struct mmc_hsq *hsq)
 		return;
 	}
 
+	mmc_hsq_modify_threshold(hsq);
+
 	slot = &hsq->slot[hsq->next_tag];
 	hsq->mrq = slot->mrq;
 	hsq->qcnt--;
diff --git a/drivers/mmc/host/mmc_hsq.h b/drivers/mmc/host/mmc_hsq.h
index aa5c4543b55f..dd352a6ac32a 100644
--- a/drivers/mmc/host/mmc_hsq.h
+++ b/drivers/mmc/host/mmc_hsq.h
@@ -10,6 +10,11 @@
  * flight to avoid a long latency.
  */
 #define HSQ_NORMAL_DEPTH	2
+/*
+ * For 4k random writes, we allow hsq_depth to increase to 5
+ * for better performance.
+ */
+#define HSQ_PERFORMANCE_DEPTH	5
 
 struct hsq_slot {
 	struct mmc_request *mrq;
-- 
2.17.1