dual processors and linux 1775

Cybrid

I am not sure what the question is that you are trying to answer.

The memory manager keeps a separate stack for each process, not each processor, and it does this whether it is UP or SMP.

I have not looked at the process scheduler lately, so things may have changed. But when I did, the thing I was interested in was whether or not the process scheduler tried to resume a process on the same processor on which it had run when it was previously suspended in order to run it on the processor most likely to have needed stuff in the processor caches. The answer was yes. Now it seems to me that that is only of value if the suspension was very recent (e.g., to handle a clock interrupt and then resume the process that was interrupted) because if a new process ran very long, the processor cache would be completely dirty as far as the former process was concerned and there would then be no point in resuming the former process on the processor it had formerly been run on. Perhaps they take this into account now. Even in the past, this was only a preference, not an absolute requirement.

I do know that the way I run this machine, putting things back on the same processor does not help at all (in the cases I have examined) because by the time a suspended process is resumed (when its IO demands have been met), the processor caches are completely dirty because I run BOINC stuff all the time and the processors are all 99% to 100% busy all the time. (See bottom line of my signature.)

-- .~. Jean-David Beyer Registered Linux User 85642. V PGP-Key: 9A2FC99A Registered Machine 241939. ^^-^^ 06:35:01 up 85 days, 20:07, 4 users, load average: 4.05, 4.11, 4.04