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From Dean Gaudet <dgau...@arctic.org>
Subject Re: roy's l_c perf patch and spareservers
Date Sat, 15 Feb 1997 03:50:58 GMT
On Fri, 14 Feb 1997, Marc Slemko wrote:

> On Fri, 14 Feb 1997, Dean Gaudet wrote:
> 
> > One idle thought I had was that we might try playing with the order of
> > things -- do the shutdown(sd,1) after a select() timeout or a successful
> > read(). 
> 
> Umm... I'm not sure that is nice.  The half close is the only way for the
> client to know that we are terminating the connection.  If we don't do it
> until later, the client won't know that the connection has been closed.
> If the client doesn't know the connection is closed, it can't close its
> half.  That would extend the lifetime of _all_ connections beyond what it 
> is right now even with lingering_close.

Well my reasoning was this... if we happen to read() everything the client
has written before we do the shutdown(), then there's a chance we won't
trigger their tcp stack lameness that causes the FIN_WAIT_2 problem.  We
should still do the shutdown(), we just might want to do it after one
read().

> > The other thing I found, just like Chuck said a while back, I played with
> > the Min/MaxSpareServers settings and removed all the huge spikes from my
> > load averages.  The change in load *could* be related to locality of
> > reference in the L2 cache, but I'm not convinced that is the only thing.
> > We're talking a difference of 50% vs 20% "cpu usage" as reported by the
> > status module.  (I'd really like to revamp status to do 5 minute rolling
> > averages.)
> 
> Played in what way?  Just increased them both?

Decreased actually.  I had them at 32/64 and lowered them to 16/32 and
it hovers around 20 idle now.  I still get the spike when I restart the
servers -- StartServers is at 64, which is roughly the mid-day median
active servers.  It starts 64, but kills a bunch early.  I'm tempted to
hack it to not kill until it's been up for a minute.

Dean


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