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SubjectRe: System freezes with high network activity
On 12/03/2011 02:04 PM, Jose Luis Salas wrote:
> Hi,
>
> attached is the output of the timer_list.
>
> With the nohz option the system is stable too.
>
> Other symptom of the problem is network drops performance to 50% ( 50 Mbps ).
>

Hey Jose,
Just following up on this old email. Looking at the timer_list.txt
that you sent, I'm not seeing anything that sticks out as problematic.
Are you still seeing issues with recent kernels (3.1, 3.2) ? Is nohz
still working for you?

I suspect the problem is that the lapic on your machine goes out to
lunch after longish idle times w/ nohz. That's why the key-press or
network traffic wakes the system back up.

Does booting with the following patch (without nohz or any clocksource=
boot args) fix the issue?

If it does, can you increase the time returned in the patch from 20ms by
powers of ten until it gets to 2 seconds or you see the problem? If the
patch below doesn't help, can you drop the value down to 1ms and let me
know if that affects anything?

thanks
-john

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 95bebaa..8fd2bfa 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -546,6 +546,9 @@ u64 timekeeping_max_deferment(void)
{
unsigned long seq;
u64 ret;
+
+ return 20000000ULL; /* 20ms */
+
do {
seq = read_seqbegin(&timekeeper.lock);



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