Improve IO throughput according to different controllers.
Make it configuable in menuconfig. Of course, there is another
implement of adjust bounce buffer size at run-time. Like:
echo 262144 > /sys/block/mmcblk0/device/bouncesz
This will reinit mmc queue when bounce size is changed.
Which is better?
On powerpc platform, 256KiB will get better perfromance than 64KiB.
I used Sandisk Extreme III Class 6, 4G memory card, tested on P1022DS
with IOzone. P1022DS memory is 1GBytes. Filesystem is ext4.
By default, bounce buffer size is 64KiB,
[root@p1022ds root]# iozone -Rab result -i0 -i1 -r64 -n1g -g2g -f /mnt/ff
KB reclen write rewrite read reread
1048576 64 12794 13260 32330 31731
2097152 64 12301 12382 18213 18239
use 256KiB as bounce buffer size,
[root@p1022ds root]# iozone -Rab result -i0 -i1 -r64 -n1g -g2g -f /mnt/ff
KB reclen write rewrite read reread
1048576 64 18533 19076 22841 23151
2097152 64 17744 17980 18333 18342
Signed-off-by: Qiang Liu <qiang.liu@xxxxxxxxxxxxx>
---
drivers/mmc/card/Kconfig | 9 +++++++++
drivers/mmc/card/queue.c | 2 +-
2 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig
index 3b1f783..3390154 100644
--- a/drivers/mmc/card/Kconfig
+++ b/drivers/mmc/card/Kconfig
@@ -50,6 +50,15 @@ config MMC_BLOCK_BOUNCE
If unsure, say Y here.
+config MMC_QUEUE_BOUNCESZ
+ int "MMC memory card bounce buffer size"
+ depends on MMC_BLOCK_BOUNCE
+ range 512 4194304
+ default "65536"
+ help
+ Provide a flexible method to adjust bounce buffer size to
+ improve the throughput according to different controller.
+
config SDIO_UART
tristate "SDIO UART/GPS class support"
help
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index dcad59c..590723f 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -20,7 +20,7 @@
#include <linux/mmc/host.h>
#include "queue.h"
-#define MMC_QUEUE_BOUNCESZ 65536
+#define MMC_QUEUE_BOUNCESZ CONFIG_MMC_QUEUE_BOUNCESZ
#define MMC_QUEUE_SUSPENDED (1 << 0)
--
1.6.4
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