mmc: hsq: Improve random I/O write performance for 4k buffers

By dynamically adjusting the host->hsq_depth, based upon the buffer size
being 4k and that we get at least two I/O write requests in flight, we can
improve the throughput a bit. This is typical for a random I/O write
pattern.

More precisely, by dynamically changing the number of requests in flight
from 2 to 5, we can on some platforms observe ~4-5% increase in throughput.

Signed-off-by: Wenchao Chen <wenchao.chen@unisoc.com>
Link: https://lore.kernel.org/r/20230919074707.25517-3-wenchao.chen@unisoc.com
[Ulf: Re-wrote the commitmsg, minor adjustment to the code - all to clarify.]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/mmc_hsq.c b/drivers/mmc/host/mmc_hsq.c
index 8556cacb21a1b4971c99144edd8531ef65771307..79836705c176237af206f877103d760062a499de 100644 (file)
--- a/drivers/mmc/host/mmc_hsq.c
+++ b/drivers/mmc/host/mmc_hsq.c
@@ -21,6 +21,25 @@ 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;
+       unsigned int tag, need_change = 0;
+
+       mmc->hsq_depth = HSQ_NORMAL_DEPTH;
+       for (tag = 0; tag < HSQ_NUM_SLOTS; tag++) {
+               mrq = hsq->slot[tag].mrq;
+               if (mrq && mrq->data &&
+                  (mrq->data->blksz * mrq->data->blocks == 4096) &&
+                  (mrq->data->flags & MMC_DATA_WRITE) &&
+                  (++need_change == 2)) {
+                       mmc->hsq_depth = HSQ_PERFORMANCE_DEPTH;
+                       break;
+               }
+       }
+}
+
 static void mmc_hsq_pump_requests(struct mmc_hsq *hsq)
 {
        struct mmc_host *mmc = hsq->mmc;
@@ -42,6 +61,8 @@ 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 aa5c4543b55f89a554d518f517304e80f0481914..dd352a6ac32acd115122a771daf0dcbc65225def 100644 (file)
--- 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;