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* [PATCH 3.3.0-rc1 1/2] do_mounts: Change the nfs-mount retry min max delays.
@ 2012-01-26 14:42 Srinivas KANDAGATLA
  2012-01-26 14:55 ` Jim Rees
  2012-01-26 15:35 ` Chuck Lever
  0 siblings, 2 replies; 9+ messages in thread
From: Srinivas KANDAGATLA @ 2012-01-26 14:42 UTC (permalink / raw)
  To: linux-nfs; +Cc: akpm, mingo, neilb, stuart.menefy, chuck.lever, bharrosh, rees

From: Srinivas Kandagatla <srinivas.kandagatla@st.com>

This patch attempts to minimize the delay in nfs root mount, which
happens as side effect of nfs-root mount retry by changing the
NFSROOT_TIMEOUT_MIN and NFSROOT_TIMEOUT_MAX values.

Current strategy is, if do_mount_root fails, sleep for 5 seconds for the
second attempt followed by a 5<<1 seconds delay for each loop with a
maximum of 30 seconds delay.
For 5 retries it would take.

	5 + 10 + 20 + 30 + 30 = 95 Seconds
with
	each do_mount_root timeout @ 3-4 seconds x 5 = 15 seconds.

Which means Kernel can only attempt the succession root-mounts or panic
after 110 seconds.

So changing min and max timeouts will have the below delays.
	0  + 1 + 3 + 7 + 15	= 26 Seconds.
and with
	each do_mount_root timeout @ 3-4 seconds x 5 = 15 seconds.
Which means Kernel can only attempt the succession root-mounts or panic
after 41 seconds

As, do_mount_root timesout in 3-4 seconds which should be sufficient
delay to start of the second nfs mount attempt and increasing delay
after that makes more sense.

I clearly see an advantange in changing these values because, Without
this patch my board mounts nfs in 9-10 seconds, however with this patch
can mount nfs in 4-5 seconds.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
---
Hello All,
With latest kernel I can see that my nfs-root mounts with big delay
of 5 seconds when compared to 2.6.32. It took 9-10 seconds, where as in 2.6.32 it took 4-5 seconds.

However with modifications to NFSROOT_TIMEOUT_MIN and NFSROOT_TIMEOUT_MAX,  nfs root mounts as it used to do it in 2.6.32.
As first nfs mount timeout itself introduces sufficient delay to start the second retry.
I think changing the min-max values will help people to nfs boot there boards faster than it is in 3.3 kernel.

Comments ?

Thanks.
srini



 init/do_mounts.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/init/do_mounts.c b/init/do_mounts.c
index ef6478f..b8214ce 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -361,8 +361,8 @@ out:
  
 #ifdef CONFIG_ROOT_NFS
 
-#define NFSROOT_TIMEOUT_MIN	5
-#define NFSROOT_TIMEOUT_MAX	30
+#define NFSROOT_TIMEOUT_MIN	1
+#define NFSROOT_TIMEOUT_MAX	32
 #define NFSROOT_RETRY_MAX	5
 
 static int __init mount_nfs_root(void)
@@ -390,7 +390,7 @@ static int __init mount_nfs_root(void)
 			break;
 
 		/* Wait, in case the server refused us immediately */
-		ssleep(timeout);
+		ssleep(timeout - 1);
 		timeout <<= 1;
 		if (timeout > NFSROOT_TIMEOUT_MAX)
 			timeout = NFSROOT_TIMEOUT_MAX;
-- 
1.6.3.3


^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2012-02-03 13:16 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-01-26 14:42 [PATCH 3.3.0-rc1 1/2] do_mounts: Change the nfs-mount retry min max delays Srinivas KANDAGATLA
2012-01-26 14:55 ` Jim Rees
2012-01-26 15:06   ` Srinivas KANDAGATLA
2012-01-26 15:35 ` Chuck Lever
2012-01-27  8:10   ` Srinivas KANDAGATLA
2012-01-27 12:34     ` Jim Rees
2012-01-30  7:46       ` Srinivas KANDAGATLA
2012-02-03 10:11     ` Srinivas KANDAGATLA
2012-02-03 13:16       ` Jim Rees

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