Re: spamd: single-core vs dual-core CPUs ?

Matus UHLAR - fantomas wrote:
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> On 05.11.08 12:09, Per Jessen wrote:[color=green]
>> I have a very unusual situation (I think):
>>
>> I am running the exact same system (it was cloned) on several
>> single-core and dual-core systems. The only difference is in the
>> hardware, i.e. some systems are dual-core.[/color]
>
> cloned? Do you have the same OS kernel with support for more CPUs and
> CPUs with more cores on both machines?[/color]

Yes, it's the same SMP kernel on all machines.
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>> I am running spamd with maxchild=25 (the actual number in use is
>> controlled externally).[/color]
>
> externally?[/color]

Sorry, I should have explained - the number of callers of spamd is being
controlled elsewhere.
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>> The single-core systems vary from two to five, sometimes six.
>> Perfectly
>> normal. On the dual-core systems, I never see more than two active
>> children. Not normal.[/color]
>
> Why not normal? Maybe the dualcore CPU can handle all mail fast enough
> so there's no need for spawning more children[/color]

OK, I also know there is a queue building up on the dual-core systems,
but hardly any queueing on the single-core.
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>> Notice that the single-core system reports "handled cleanup of child
>> pid nnnnn due to SIGCHLD" which is never seen on the dual-core
>> system, and that the dual-core reports "child nnnnn killed
>> successfully", which is
>> never seen on the single-core system. What am I missing here?[/color]
>
> While I am not sure what do those messages mean, I think that there
> should be no difference between handling of processes independently on
> number of CPUs/cores whatever. I guess that's problem of OS, not SA.[/color]

Quite probably, but the symptoms are showing in SA, not in the OS :-)
Also, in 3.1.7 this all worked just fine, although with a different
kernel version.


/Per Jessen, Zürich