Latest FC kernel still have SMP bugs?

Norman Gaywood norm at turing.une.edu.au
Tue Apr 6 22:14:30 UTC 2004


On Tue, Apr 06, 2004 at 03:38:21PM +0100, Nigel Wade wrote:
> Nigel Wade wrote:
> >Norman Gaywood wrote:
> >>On Fri, Apr 02, 2004 at 11:31:06AM +0100, Nigel Wade wrote:
> >>>Unfortunately, RH9/RHEL3 don't have the version of LDAP I require, 
> >>>and when I tried an upgrade to openldap I started getting FUTEX 
> >>>locking problems.
> >>Install the RHEL3 kernel on FC1. I installed:
> >>
> >>kernel-smp-2.4.21-9.0.1.EL
> >>kernel-smp-unsupported-2.4.21-9.0.1.EL
> 
> Ok, the bottom line is that this doesn't work either.
> 
> I've built the RHEL3 kernel on FC1 and run the system up using this. 
> Ordinary ldap requests seem quite happy, but I'm still seeing the futex 
> lock problem with nss_ldap. E.g. when I add 'hosts: files ldap dns' to 
> /etc/nsswitch.conf I get:
> 
> # strace ping host
> munmap(0xb75ff000, 4096)                = 0
> uname({sys="Linux", node="hostname", ...}) = 0
> futex(0x53e4ec, FUTEX_WAIT, 2, NULL

Interesting. I thought the EL kernel had the fast futex code back-ported
but I have not checked this. So I thought the EL kernel would work like
RH9 and FC1 kernels.

Could I ask what what steps you took to build the EL kernel on FC1? I
didn't have much luck building with rpmbuild when I tried this.

> Setting LD_ASSUME_KERNEL=2.4.1 cures this particular problem, but isn't a 
> solution for a system relying on LDAP for all authentication and NSS 
> functions.

Another suggestion for you to try is on one of the bugzillas. That is,
to rebuild the FC1 kernel with low latency scheduling turned off. Maybe
that's your best option.

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=109962

Comments #42 and #44

-- 
Norman Gaywood, Systems Administrator
School of Mathematics, Statistics and Computer Science
University of New England, Armidale, NSW 2351, Australia

norm at turing.une.edu.au            Phone: +61 (0)2 6773 2412
http://turing.une.edu.au/~norm    Fax:   +61 (0)2 6773 3312

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