Re: ipvs_syncmaster brings cpu to 100%

On Mon, Sep 26, 2005 at 05:05:10PM +0900, Horms wrote:

[snip]

quoted

quoted

quoted

quoted

Furthermore, if I make an "rgrep" in the source tree of kernel 2.6.12
the function schedule_timeout() is more used than the ssleep() (517
occurrencies vs. 43), so why in ip_vs_sync.c there was this change?

The other oddity is that Horms reported on this list that on non Xeon
CPU the same version of kernel of mine does not present the problem.

I'm getting crazy :-)

I've prepared a patch, which reverts the change which was introduced
by Nishanth Aravamudan in February.

Was the 100% cpu utilization only occurring on Xeon processors?

That seems to be the only case where were this problem has been
observed. I don't have such a processor myself, so I haven't actually
been able to produce the problem locally.

One reason I posted this issue to netdev was to get some more
eyes on the problem as it is puzzling to say the least.

quoted

Care to try to use msleep_interruptible() instead of ssleep(), as
opposed to schedule_timeout()?

I will send a version that does that shortly, Luca, can
you plase check that too?

Here is that version of the patch. Nishanth, I take it that I do not
need to set TASK_INTERRUPTABLE before calling msleep_interruptible(),
please let me know if I am wrong.

Luca, please test.

-- 
Horms

*UNTESTED*

Use msleep_interruptible() instead of ssleep() in ip_vs_sync daemon,
as the latter seems to cause 100% CPU utilistaion on HT Xeons.

Discussion:
http://archive.linuxvirtualserver.org/html/lvs-users/2005-09/msg00031.html

Reverts:
http://www.kernel.org/git/?p=linux/kernel/git/tglx/history.git;a=commit;h=f8afb60c7537130448cc479d6d8dc9bf4ee06027

Signed-off-by: Horms <horms@verge.net.au>

diff --git a/net/ipv4/ipvs/ip_vs_sync.c b/net/ipv4/ipvs/ip_vs_sync.c
--- a/net/ipv4/ipvs/ip_vs_sync.c
+++ b/net/ipv4/ipvs/ip_vs_sync.c

@@ -655,7 +655,7 @@ static void sync_master_loop(void)
 		if (stop_master_sync)
 			break;
 
-		ssleep(1);
+		msleep_interruptible(1000);
 	}
 
 	/* clean up the sync_buff queue */

@@ -712,7 +712,7 @@ static void sync_backup_loop(void)
 		if (stop_backup_sync)
 			break;
 
-		ssleep(1);
+		msleep_interruptible(1000);
 	}
 
 	/* release the sending multicast socket */

@@ -824,7 +824,7 @@ static int fork_sync_thread(void *startu
 	if ((pid = kernel_thread(sync_thread, startup, 0)) < 0) {
 		IP_VS_ERR("could not create sync_thread due to %d... "
 			  "retrying.\n", pid);
-		ssleep(1);
+		msleep_interruptible(1000);
 		goto repeat;
 	}
 

@@ -858,7 +858,7 @@ int start_sync_thread(int state, char *m
 	if ((pid = kernel_thread(fork_sync_thread, &startup, 0)) < 0) {
 		IP_VS_ERR("could not create fork_sync_thread due to %d... "
 			  "retrying.\n", pid);
-		ssleep(1);
+		msleep_interruptible(1000);
 		goto repeat;
 	}