Re: [exim] Performance considerations

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Autor: Edgar Lovecraft
Fecha:  
A: exim-users
Asunto: Re: [exim] Performance considerations
Nigel Metheringham wrote:
>
> On Mon, 2004-09-06 at 23:19 -0500, Edgar Lovecraft wrote:
> > Also a note, the size of exim varies on what features you compile into
> > the binary, only compile those things that you need, as an example,
> > I have 3 different 'versions' of exim on three different servers, as
> > they all do different things, they do not need the same features, and
> > none of them need ALL of the features. (such as one machine talks only
> > to other internal exim servers, as such, it only accepts mail from
> > those servers, so there is no type of SMTP auth or encryption compiled
> > in, as the network it is on, is already private, even from clients)
>
> Frankly this will make zippo difference to the amount of memory used by
> exim on a machine.


How so? If I do not need the support, and I do not compile it in, then
I never have to worry about it taking up any space at all, memory or
otherwise.

>                The code size will be shared between all the
> running exim processes,


Someone else had already pointed out that they needed to go research
how shared memory works, and I already know that, so why restate what
has already been said.

                  and so the only difference is in the data size

> used by the binary - and in general if you don't have configuration for
> a feature it won't be taking up additional data size (ie if you have
> compiled in mysql but don't configure it in the config file then there
> will be zero overhead in memory terms for mysql, and a minimal overhead
> in cpu cycles when doing a lookup).


Are you sure about that? If that is true, then why is there an explicite
setting to not load perl support until it is needed? Besides, why
compile in support that you will never use.

> > here are the 'sizes' of the exim binary files as found by 'ls'
> > the exim version is 4.34, and these all have perl compiled in,
> > remove perl and the size reduces by '56276', remove LDAP support
> > and drop the size by another '13730'
>
> serious falacy here....
> If you are using perl, then the memory overhead is going to be several


Ahem, I did not give actuall figures for the memory used, however, I
did say this as well, just not in so many words...

Just in case you missed it, here it is from my previous post were I
CLEARLY stated that the binary size and memory footprint do not have
a one-to-one correlation.

-----from my previous post------
Now I know that binary size, memory footprint, and such things do not
have a one-to-one correlation, but my point is really to just say that
your memory footprint with exim is going to have a direct correlation
to what features you actually compile into the binary, and don't forget
that if you use virus/spam scanners during the SMTP transaction, the
MTA memory footprint will basically be a non-issue, as the virus/spam
scanners are what is going to take up the system memory.
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