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From Dean Gaudet <dgau...@arctic.org>
Subject Re: Patch to slow down children's deaths
Date Wed, 08 Jan 1997 01:14:40 GMT
I've done this with side-by-side machines handling equal portions of the
load.  The machine that had been running would be in steady state with 70
to 80 active children, and another 40 waiting, and 13 hits per second. 
The other machine, which I had just restarted, would have 0 inactive
children for most of a minute and ramp from 3 to 4 hits per second up to
13 hits per second after a minute.  So essentially for that minute the
machine was hardly serving the load it could serve. 

Yeah I could just beef up maxfree, but I'm not sure that's correct either. 
Consider that the same machine might do a lot of log crunching at night
when it doesn't need 90 spare servers...

Dean

On Tue, 7 Jan 1997, Cliff Skolnick wrote:

> 
> So if your load is 20/second, start 20 or 25 and why would you have
> maxfree <20 or 30.  Your machine will mostly be pretty beefy and dedicated
> with a load like that :)
> 
> One per second...so most servers would reach steady state in less than a
> minute, maybe a couple minutes for very large servers.  It would be nice 
> to have some hard data here.  Does anyone record hits/second verses 
> number of active chilren on a web server?  It would be interesting to 
> look at the graph and figure out what to do from there.  Anyone care to 
> share?
> 
> On Tue, 7 Jan 1997, Dean Gaudet wrote:
> 
> > It starts one per second, and if your load is 20 hits per second that is a
> > serious performance bottleneck.
> > 
> > Dean
> > 
> > On Tue, 7 Jan 1997, Cliff Skolnick wrote:
> > 
> > > On Tue, 7 Jan 1997, Ed Korthof wrote:
> > > 
> > > > A while ago, I posted about the rate at which children die.  It's
> > > > basically immediate, and children die until we're down to MaxFreeServers;
> > > > this interfears with StartServers for large web sites, since
> > > > StartServers > MaxFreeServers (as is reasonable) means the following
> > > > occurs:
> > > 
> > > I think apache should print a warning, since these values conflict with
> > > each other in a logic sense to me and aparently apache does not like it
> > > either. 
> > > 
> > > Also can someone explain why a large start servers is better than letting
> > > apache start more as the load rises?  I would think you simply trade off a
> > > few seconds of unavaliablity at startup for a slightly higher latency on
> > > http requests untila steady state is reached. 
> > > 
> > > --
> > > Cliff Skolnick, Technical Consultant
> > > Steam Tunnel Operations
> > > cliff@steam.com, 415.297.5938
> > > http://www.steam.com/
> > > 
> > > 
> > 
> > 
> 
> --
> Cliff Skolnick, Technical Consultant
> Steam Tunnel Operations
> cliff@steam.com, 415.297.5938
> http://www.steam.com/
> 
> 


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