Hi all,
What about this feature? Provide a method of adjust mmc bounce size through menuconfig
or /sys/block/mmcblk0 at run-time. Which one is better?
Do you have any ideas? Thanks for your advice.
________________________________________
From: Liu Qiang-B32616
Sent: Friday, November 04, 2011 4:54 AM
To: linux-mmc@xxxxxxxxxxxxxxx
Cc: cjb@xxxxxxxxxx; Li Yang-R58472; Gala Kumar-B11780; Liu Qiang-B32616; Liu Qiang-B32616
Subject: [PATCH] [RFC/PATCH] SD/MMC: support adjust bounce buffer size dynamically in menuconfig
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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