On Fri, 2 Nov 2007 7:47 am, Gary Sewell wrote:
> Firstly, we are running a mod_perl application on 4 separate servers=20
> due to its bulkiness.


How many requests per second are you processing with each machine? Have=20
you looked at profiling your application?

> We have found each apache instance is almost double on the 64-bit=20
> servers
> Example 64-bit
>
> USER=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 PID %CPU %MEM=C2=A0=C2=A0=C2=A0 =

VSZ=C2=A0=C2=A0 RSS TTY=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 STAT=20
> START=C2=A0=C2=A0 TIME COMMAND
>
> www-data=C2=A0 9950=C2=A0 2.4=C2=A0 1.7 210324 141744 ?=C2=A0=C2=A0=C2=A0=

=C2=A0=C2=A0=C2=A0 S=C2=A0=C2=A0=C2=A0=20
> 14:26=C2=A0=C2=A0 0:11=C2=A0 \_ /usr/sbin/apache-perl
>
> Example 32-bit
>
> USER=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 PID %CPU %MEM=C2=A0=C2=A0=C2=A0 =

VSZ=C2=A0=C2=A0 RSS TTY=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 STAT=20
> START=C2=A0=C2=A0 TIME COMMAND
>
> www-data=C2=A0 2336=C2=A0 0.0=C2=A0 2.7 117100 105908 ?=C2=A0=C2=A0=C2=A0=

=C2=A0=C2=A0=C2=A0 S=C2=A0=C2=A0=C2=A0=20
> 15:14=C2=A0=C2=A0 0:16=C2=A0 \_ /usr/sbin/apache-perl
>
> Is this something we just put up with or have we done something=20
> drastically wrong?


Iirc, the calculations for shared memory on linux aren't always=20
accurate, but toersten may have released something that addressed this,=20
linux::smaps I think. As a comparison, I have commonly seen apps that=20
take over 500 megs total process memory, but most of that is shared or=20
data. I've seen java apps or php apps take up comparatively as much=20
memory.
>
> Is it worth installing a 32-bit distribution on the 64-bit processors?=20
> Will the 8Gb RAM cause problems as 32-bit distributions if we did this?


Probably not worth it. I run mod_perl on a 64 bit machine with 16 gigs=20
and no problems.

> How can I get a split/rundown of what is taking up so much memory for=20
> each apache instance, 100Mb is a lot, let alone 200Mb on the 64 bit=20
> servers. I=E2=80=99m sure we are going wrong somewhere.


Apache2::Status will give you a detailed breakdown of where your memory=20
is used.


>
> Many Thanks.
>
> GS
>
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