Re: System resource useage abnormalities

Matti Aarnio (
Thu, 1 May 1997 13:22:51 +0300 (EET DST)

> Qmail was running just fine on my P133, but that machine had to go away
> and I installed qmail and SmartList on my 266Mhz UDB Alpha. The kernel is
> 2.0.27 and distrib RedHat 4.1. This machine isn't one of those great
> powerhouse Alpha's, but it should be a little better than a P133. Instead,
> I am finding that the load average is unusually high and the system
> somewhat slow in delivering mail for no good reason. Here's a typical view
> from top.

It is not about your host performance...
> A very dead system. Nothing unusual happening. Minimal interrupts/second
> and context switching. But there's a high load average with 60% cpu idle
> time. The top just didn't happen to catch the cpu while waiting on disk,
> it's averaging 60%. I'm sending lots of mail through the mailing list.
> It's on cablemodem now as opposed to T1 when I had the list on the P133.
> Not sure how this would cause such a high load with low cpu useage.

The cablemodem has fairly fast channel from the network to
your machine, but SLOW link the other way. (64-200 kbps)

Part of the problem is that Qmail sends all smtp sessions in
parallel, which effectively kills your already meager outbound
bandwidth (and your machine). "In parallel" meaning:
For each recipient address on EACH message it runs individual
smtp transporter process. You have 10 messages with 20
addresses --> you have 200 smtp transporters running...

> Anyone have any ideas?

You need to have a T1 connected service provider that is willing
to do the actual distribution of the smtp messages.
Then you define message routing so that all non-local traffic
is sent to that server.

> ----------
> Tracy Reed

/Matti Aarnio <>
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