On my machines I do not run a named, but rather use my ISP's servers.
This increases the chance of a cache hit from dns simply because their
servers to way more lookups than I would ever do alone. So for my
setup, nscd helps quite a bit.
I have servers running other applications that have seen as much as a
20% increase in performance because I started using nscd (they are
print servers at my work).
I don't see any of the issues anyone here has described, because my
system only has a few cocurrent pop connections anyways. Regardless,
it is still worth a try.
-adam
On 5/4/06, Chris Hemsing <C.Hemsing (at mark) gmx.net> wrote:
> Hello Adam,
>
> there should be a named running anyway!!!!!!!!!!!!
> Of course named is cacheing!!!!
> But - of course - you need to ask your own named.
> So resolv.conf should direct to
> 127.0.0.1
> No further use in a cache daemon!
>
> It is just a fact, that there are very many lame nameservers out
> there.
>
> Therefore, reverse namelookups are potentially extremely slow and therefore there
> exists an option to switch them off.
>
> The point is: do you want the (reverse) name in the logs rather
> than the ip address?
> I alway have the reverse name lookups switched off.
> If I'm keen to know the reverse name I can look it up later.
> qpopper just waits for the name lookup before it can do the log entry.
>
> Chris
>
> Thursday, May 4, 2006, 4:04:35 PM, you wrote:
>
> AC> Something that may be worth a try is to run the nscd daemon and leave
> AC> reverse lookups on in qpopper.
>
> AC> If you have connections from the same client multiple times, this will
> AC> greatly speed up the dns lookups. It should have little effect on a
> AC> new connection however.
>
> AC> -Adam
>
> AC> On 5/4/06, Brian N. Smith <brian (at mark) nuonce.net> wrote:
> >> To all,
> >>
> >> I have had this problem to. Yesterday I made a very small change, and I
> >> "think" it seems to have cleared it up some. KNOCK on wood, but I haven't
> >> received any Active Monitor emails about CPU Utilization, or any complaints
> >> at all.
> >>
> >> I know eventually it will be switched to Dovecot, but if anyone wants to try
> >> my "magical" fix.
> >>
> >> Edit: /etc/xinetd.d/pop3
> >>
> >> Change: server_args = in.qpopper -s
> >> To: server_args = in.qpopper -s -R
> >>
> >> The -R says NOT to do a reverse lookup. Like I said, remarkably it seems to
> >> have fixed it. I haven't seen 10-15 POP3 processes like I have been seeing.
> >> It seems to have made the box very happy. If someone who is having the same
> >> problem can try it, and let me know if I am smoking crack, or does this
> >> actually make a big difference?
> >>
> >> The only thing that I noticed to, is that PAM is just sometimes really slow.
> >> Any good how-tos on speeding it up?
> >>
> >> Thanks,
> >> Brian
> >>
> >>
> >>
>
>
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