Latest FC kernel still have SMP bugs?

[Nigel Wade]

Mitch Wiedemann wrote:
> Is the FC1 2.4.22-1.2174.nptl kernel still having problems with SMP and 
> hanging?
> I'm due to install some MP servers soon and want to avoid problems 
> (imagine that!).
> 
> If said kernel is still having trouble, what's the easiest fix?
> 
> Thanks in advance.
> 

I'm currently investigating SMP here. When I tried stock FC1 and the latest 
2.4.22-1.2174.nptl I had severe problems with LDAP. I didn't get any hard 
lockup, but I would have delays of between 4 and 300 secs in LDAP response 
times. I have a strong suspicion that the delays are related to FUTEX, but 
that's hard to prove.

I found that disabling hyperthreading is the answer to my problems. When I 
disabled it in the BIOS LDAP started behaving itself.

I'm currently stress testing the LDAP server and it's managing ~40,000 
requests per minute with the peak search times of around 5ms. I read in some 
other threads that mounting/unmounting NFS and Samba filesystems lead to 
hard lockups so I'm mounting/listing/unmounting one of each every half hour. 
The test will be left running for the next 72 hours to see what happens...


-- 
Nigel Wade, System Administrator, Space Plasma Physics Group,
             University of Leicester, Leicester, LE1 7RH, UK
E-mail :    nmw at ion.le.ac.uk
Phone :     +44 (0)116 2523548, Fax : +44 (0)116 2523555