Peter Buckingham <[EMAIL PROTECTED]> wrote:
> Eric Enright wrote:
> > Linux overcommits / lazy loads on memory allocations, though this is
> > tunable. I believe the default setting is to overcommit, which can
> > lead to the random killing of processes in order to retrieve memory
> > should one run out. I forget the terminology used for that particular
> > system.
>
> They have something called the 'out of memory killer'. In the past it
> just looked for Netscape/Mozilla ;-) I believe its behaviour is tunable,
> at one point they actually allowed the determination of processes to be
> killed to be modifiable.
>
> There also was some effort to remove this behaviour in the 2.4 kernel.
I am not sure about the behavior on 2.6 but I was forced to upgrade the berlios
web server from Linux-2.4 to Solaris 3 years ago, after the web service did
cause
Linux to go into catatony every 30 minutes caused by the memory overcommitment.
There is no problem on single CPU systems and this is why a home PC driven
development like Linux does not address the problem. If you however have a dual
CPU machine, the kernel will do copy on write faster than it is able to kill
processes :-( as a result, only reset or power cycling the machine helps....
What happend is that apache preforks at startup time, resulting in many times
mmemory overcommitment if you follow the apache server hints in the log files
and increase the nhumber of forked instances. Once you get severyl hundreds of
HTTP requests per second, the serve will modify the data section causing a copy
on write and immediate starvation of the machine.
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
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