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Date: Sun, 3 Nov 2002 23:59:05 +0300
From: Solar Designer <>
Subject: Re: performance under solaris

On Sun, Nov 03, 2002 at 01:12:54PM -0600, J.D. Bronson wrote:
> At 01:02 PM 11/3/2002, you wrote:
> >On Sun, Nov 03, 2002 at 07:25:09AM -0600, J.D. Bronson wrote:
> >> However, with popa3d I see pauses (although not of any duration to 
> >speak of)
> >> when grabbing this same exact mail spool file.  grab-pause-grab-pause and
> >> so on...
> >
> >How long are the pauses?
> 1-2 seconds....enough to be noticed, but not enough to be a problem :-/

This may be caused by dropped packets, 1-2 seconds is what it may take
before a packet is retransmitted on a LAN.

> OTOH, since running spop3d or qpopper result in higher performance, I doubt 
> there is anything on my network that needs fixing......:-/

Wrong conclusion.

Although may turn out to be not network, but network stack configuration
on one of the ends (Solaris?)

I really suggest that you investigate with tcpdump.  It is likely that
you will see retransmits.

> However, I am presuming that these programs make use of something in a 
> different manner than popa3d

Yes.  popa3d sends more data at once to the kernel and thus probably
to the network.  Normally this results in better efficiency, but it's
also more likely to trigger problems in the network.

> and hence I was wondering what tweaks (if any) 
> are available to popa3d...if there is nothing, it was simply worth asking.

Why, I told you of one: reduce RETR_BUFFER_SIZE.

> I am satisfied with popa3d, but always looking for speed improvements.
> I am installing an xBSD machine and will test popa3d on there for a simple 
> comparison. Some POP3 daemons fly on some OS's and others fail miserably 
> with performance.

Basically, those which copy mailboxes (like qpopper) are the slowest.

If qpopper turns out to be faster for you, this is clear indication of
a bug somewhere.

Also, normally performance differences are differences in server load,
not some "pauses".


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