Re: ipvs_syncmaster brings cpu to 100%

[Horms <horms@xxxxxxxxxxxx>]

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 <liuk001@xxxxxxxxx> wrote:
> >
> > 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 <wensong@xxxxxxxxxxxxxxxxxxxxxx>
> >
> > Is Wensong still the maintainer for this code?

Yes, although he is kind of quiet.

> > 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@xxxxxxxxxxxx>

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;
        }