+ block-ps3-fix-slow-vram-io.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     block/ps3: fix slow VRAM IO
has been added to the -mm tree.  Its filename is
     block-ps3-fix-slow-vram-io.patch

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------------------------------------------------------
Subject: block/ps3: fix slow VRAM IO
From: Hideyuki Sasaki <Hideyuki_Sasaki@hq.scei.sony.co.jp>

The current PS3 VRAM driver uses msleep() to wait for completion of RSX
DMA transfers between system memory and VRAM.  Depending on the system
timing, the processing delay and overhead of this msleep() call can
significantly impact VRAM driver IO.

To avoid the condition, add a short duration (200 usec max) udelay()
polling loop before entering the msleep() polling loop.

Signed-off-by: Hideyuki Sasaki <xhide@rd.scei.sony.co.jp>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Jim Paris <jim@jtan.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/ps3vram.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff -puN drivers/block/ps3vram.c~block-ps3-fix-slow-vram-io drivers/block/ps3vram.c
--- a/drivers/block/ps3vram.c~block-ps3-fix-slow-vram-io
+++ a/drivers/block/ps3vram.c
@@ -123,7 +123,15 @@ static int ps3vram_notifier_wait(struct 
 {
 	struct ps3vram_priv *priv = ps3_system_bus_get_drvdata(dev);
 	u32 *notify = ps3vram_get_notifier(priv->reports, NOTIFIER);
-	unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
+	unsigned long timeout;
+
+	for (timeout = 20; timeout; timeout--) {
+		if (!notify[3])
+			return 0;
+		udelay(10);
+	}
+
+	timeout = jiffies + msecs_to_jiffies(timeout_ms);
 
 	do {
 		if (!notify[3])
_

Patches currently in -mm which might be from Hideyuki_Sasaki@hq.scei.sony.co.jp are

block-ps3-fix-slow-vram-io.patch