Re: ipvs_syncmaster brings cpu to 100%

On Fri, Sep 23, 2005 at 11:15:31AM -0400, Roger Tsang wrote:

As I've said before in this thread, you might want to try changing all the
ssleep() calls to schedule_timeout().

Roger


On 9/22/05, Luca Maranzano [off-list ref] wrote:

quoted

Hello all,

here again trying to discover the reason ot the CPU hog for
ipvs_sync{master,backup}.

I've digged in the sources for ip_vs_sync.c and the main differences
between kernel 2.6.8 and 2.6.12 is the use of ssleep() instead of
schedule_timeout().

The oddity I've seen is that in the header of both files, the version
is always like this:

* Version: $Id: ip_vs_sync.c,v 1.13 2003/06/08 09:31:19 wensong Exp $
*
* Authors: Wensong Zhang [off-list ref]

Is Wensong still the maintainer for this code?

Yes, although he is kind of quiet.

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.

I have CCed him, Dave Miller, Wensong Zhang, Julian Anastasov, and the
netdev list for comment. 

Could intererested parties please test the patch.

Thanks

-- 
Horms

Use schedule_timeout() 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 +655,9 @@ static void sync_master_loop(void)
 		if (stop_master_sync)
 			break;
 
-		ssleep(1);
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(HZ);
+		__set_current_state(TASK_RUNNING);
 	}
 
 	/* clean up the sync_buff queue */

@@ -712,7 +714,9 @@ static void sync_backup_loop(void)
 		if (stop_backup_sync)
 			break;
 
-		ssleep(1);
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(HZ);
+		__set_current_state(TASK_RUNNING);
 	}
 
 	/* release the sending multicast socket */

@@ -824,7 +828,9 @@ 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);
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(HZ);
+		__set_current_state(TASK_RUNNING);
 		goto repeat;
 	}
 

@@ -858,7 +864,9 @@ 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);
+		__set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(HZ);
+		__set_current_state(TASK_RUNNING);
 		goto repeat;
 	}