On 24 Nov, Stefan G. Weichinger wrote: > Stefan G. Weichinger schrieb: >> Stefan G. Weichinger schrieb: >> >>> Since then no crashes, but I would have to test clicking some more stuff >>> to really believe ... >> >> As always, after hitting SEND ... one more crash ... > > Sometimes it crashes after clicking opera, sometimes after clicking > thunderbird, so far never when clicking/starting a gnome-terminal. > > I am still looking for a pattern or an error-message somewhere ... >
This reminds me of a problem we had just recently. Have you got a multi-core CPU ? If yes, read on. We have 6 machines here running an identical Gentoo system (just different hostname and IP number) with a AMD Phenom II quad core CPU and identical mother boards. One of them had these random crashes you reported. I've totured memory by running up to 3 memtester-processes over night - no single fault. Our dealer has replaced the motherboard - again no change. Then I suspected the CPU itself although it has stood a burnK7 run for several hours. After the CPU has been replaced the spook has gone. I suspect a cache coherence problem. The normal memory tests assign a given window of the physical storage to a given core - even if run in parallel. But a typical usage under Linux switches the core which executes a given thread quite frequently. Now the Phenom II has 4 core each with a private 0.5 Mb primary cache but a 6 Mb second level cache common to all 4 cores. In the BIOS one can opt for all 4 cores using this secondary cache or for only a single core using it. When a core writes to this cache or to memory all other cores must be informed that their private cache is invalid. If this doesn't happen or happens a bit too late, a core will fetch invalid (old) memory contents which may result in a crash. So, if you can, set the BIOS switch that only a single core can use the secondary cache. If the problems disappears the CPU is broken. I hope you can solve your problem, Helmut. -- Helmut Jarausch Lehrstuhl fuer Numerische Mathematik RWTH - Aachen University D 52056 Aachen, Germany
