Unstable clock on BL685c + RHEL3 U8 hugeme kernel

[el pinco]

We discovered a strange behaviour of the clock on our BL685c running Redhat 3 ES + kernel hugemem (8 GB). The node is a 4-cpu Opteron dual core.

The problem seems to be related with the kernel and the BL685c, in other hosts with the same kernel but different hardware the problem is not present:


$ while true ; do date ; done
[...]
Fri May 25 11:26:46 CEST 2007
Fri May 25 11:26:46 CEST 2007
Fri May 25 11:26:46 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:46 CEST 2007
Fri May 25 11:26:46 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
[...]
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:49 CEST 2007
Fri May 25 11:26:49 CEST 2007
Fri May 25 11:26:49 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
Fri May 25 11:26:47 CEST 2007
[...]

[el pinco]

Hi, we repeated the test using others BL685 blades with the same hardware configuration and we observed that the problem is present in all machines running RHEL3 + updates, while running RHEL4 the clock is ok.

A similar hardware configuration but not blade (DL 585) with the same operating system is working correctly.