linux-kernel - [PATCH] drivers/char/hvc_console.c: reduce max idle timeout

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Message-Id: <201010271659.o9RGxrMc009847@farm-0002.internal.tilera.com>
Date:	Wed, 27 Oct 2010 12:54:27 -0400
From:	Chris Metcalf <cmetcalf@...era.com>
To:	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] drivers/char/hvc_console.c: reduce max idle timeout

The tile architecture uses this framework for our serial console,
and our users complain that the delay of up to two seconds feels like
the machine has gone non-responsive and is disturbing.  By contrast,
a delay of up to half a second feels like just the normal sort of
delay caused by swapping, network lag, etc. and is not noticeable.
The overhead is obviously not much greater.

Signed-off-by: Chris Metcalf <cmetcalf@...era.com>
---

I'm happy to push this via the tile tree if the linuxppc-dev folks
want to give me an acked-by, or you can take it into your tree.  Thanks!

 drivers/char/hvc_console.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 3afd62e..1df5431 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -565,11 +565,11 @@ static int hvc_chars_in_buffer(struct tty_struct *tty)
  * and during console activity we will use a default MIN_TIMEOUT of 10.  When
  * the console is idle, we increase the timeout value on each pass through
  * msleep until we reach the max.  This may be noticeable as a brief (average
- * one second) delay on the console before the console responds to input when
+ * 0.25 second) delay on the console before the console responds to input when
  * there has been no input for some time.
  */
 #define MIN_TIMEOUT		(10)
-#define MAX_TIMEOUT		(2000)
+#define MAX_TIMEOUT		(500)
 static u32 timeout = MIN_TIMEOUT;
 
 #define HVC_POLL_READ	0x00000001
-- 
1.6.5.2

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