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Joseph Shraibman wrote:
> Ulisses Reina Montenegro wrote:
> > Ben Ricker wrote:
> >
> > > I am pitching Jserv against iPlanet tomorrow and I had one more
> > > question. iPlanet claims to have multi-processor support built in (I
> > > thought the OS handeled that). I wanted to get something clear: what
> > > support does Apache/Jserv provide for multip processor machines?
> > >
> > > I thought I read somewhere that Apache is not multip processor aware. Is
> > > this true?
> >
> > Yes, multiprocessor support on Apache/JServ depends on the OS you're using.
> > We use Linux, so that is what I can talk about. In Linux, the granularity of
> > load-balancing between processors is a process. That means that, if you have
> > some heavy computation going on, better divide it between two or more
> > processes, so that the OS can load-balance them.
> >
>
> What??? For what version of Linux?
AFAIK, up to 2.2.x, I really don't know about the 2.4.x series (which are not in
production yet, anyway). That is easily monitored using 'top', which will never
show you a process using more than 100% of a CPU's time. Under AIX, for example,
on a SMP machine heavy processes will show up using up to n*100% of CPU time,
where n is the number of CPUs. So, when JServ is run under a JVM with green
threads on a multiprocessor machine, it will use only CPU. You can test that
easily. On a single-processor machine and a SMP machine, do
cat /dev/urandom | gzip -9 > /dev/null &
cat /dev/urandom | gzip -9 > /dev/null &
On the single-processor machine you'll easily verify with top or any other
CPU-usage monitoring tool that both gzip's consume about 50% of CPU time. On a
SMP-machine, each gzip will be allocated it's own CPU, where they can grow to
about 95%-99% of CPU usage. That also proves that top does not show usage CPU
usage accounting for the whole machine, only for a single processor on the machine
(that is, a process that uses 50% CPU time on a dual-processor machine is *not*
using a whole processor for itself -- only half of one processor).
Hope that clarifies some points. Even though this is not JServ-talk, I believe it
is of interest to many in the list who run JServ under Linux.
Regards,
Ulisses Montenegro
Systems Administrator/RADIX
http://www.radix.com.br/
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