Re: signifanctly slowdown of FreeBSD 8.0-CURRENT/amd64

Hi,

I have a similar problem, for about 3 weeks/1 month now, on a SMP box.
If i run something using much cpu for a "long" time and/or causing heavy
I/O, like compiling or watching a video, my box slows down a lot, X11
(and any apps, X11 or not) become much less responsive, the CPU stays at
100% load (mainly because of X11), even when the original task is ended.
If I stop X11, the system stay still very slow. The only way to get my
machine back in a usable state is to reboot it... :(

Following this discussion, I've tried to compile a kernel (with a fresh
check out from yesterday) with and without adaptive sx, and it didn't
change anything at all, so this is not the origin of the problem.

I've no idea from where the problem comes from, and I can't say exactly
since when it is here. But I can give more informations about my system
if needed and test any solution you could advise if any.

Thanks!

Pierre Guinoiseau


O. Hartmann wrote:
> Kip Macy wrote:
>>> I'm running the r193133 amd64 with a custom kernel and all debugging off
>>> on an AMD Athlon64 3400+ single-core, and I haven't noticed any significant
>>> slowing, although I haven't been doing any systematic benchmarking.
>>>
>>> What would be the penalties of running an SMP -CURRENT kernel on
>>> single-core hardware with no hyperthreading? Can anyone quantify the
>>> typical added overhead?  Or, counterintuitively, would an SMP kernel
>>> be better in some ways?
>>>
>>>     
>> He is trying to diagnose if the problem was introduced by enabling
>> adaptive spinning on sx locks. They're only enabled on SMP kernels.
>>
>> Cheers,
>> Kip
>>   
> Well, no SMP on UP AMD CPUs without SMT means no usage of the sx locks.
> As far as I know, the sx locks were introduced a couple of days ago,
> weren't they?
> 
> To avoid any kind of misunderstanding, there is no permanent 'slowdown',
> it occurs especially whenever the system's compiler builds world or a
> kernel or heavy I/O activities occur. It seems my boxes, especially the
> UP box, is freezing, no reaction on X11. Well, first time I thought it
> is related to UP, low memory or especially new drm code used with X11
> for acceleration, but I also realized those 'slowdown-incidents' on
> boxes with multicores, 8 or more GB of RAM and no X11 installed and
> running. This performance impact in  situations whenever building a
> world is significant. We did not change the compiler, it is still the
> old gcc 4.2, so I do not expect  an impact from new high-memory and
> cpu-consuming optimization routines. I do not even benchmark my boxes
> day for day, but I usually do a set of the same work on those boxes used
> for scientific work, so while building world even on SMP boxes and
> working after installation with the same software set reveals some
> weirdness in some points.
> 
> I thought this is due some use-uninterruptable debugging switches, some
> wrote the malloc code is about to change and so on so I was wondering if
> there is something temporarely going on at the moment where some hints
> could prevent me from building a world within this testing phase. Just
> speculation.
> 
> Greetings,
> Oliver
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