Miscellaneous questions

Dag-Erling Smørgrav des at linpro.no
Wed Feb 13 16:41:26 CET 2008

"Poul-Henning Kamp" <phk at phk.freebsd.dk> writes:
> "Michael S. Fischer" <michael at dynamine.net> writes:
> > (1) Feature request: Can a knob be added to turn down the verbosity of
> > Varnish logging?  Right now on a quad-core Xeon we can service about
> > 14k conn/s, which is good, but I wonder whether we could eke out even
> > more performance by quelling information that we don't need to log.
> The shared memory log is practically free, the trick is to only
> pick the stuff out of it that you need to store on disk.

I believe varnishlog -w /var/log/varnish.log is enabled by default if
you install from packages on !FreeBSD.  We may want to change this.

> > (2) HTTP/1.1 keep-alive connection reuse:  Does Varnish have the
> > ability to reuse origin server connections (assuming they are HTTP/1.1
> > Keep-Alive connections)?  Or, is there a strict 1:1 mapping between
> > client-proxy connections and proxy-origin server connections?
> They should already be reused by default.

Maybe something is preventing backend session reuse in his
installation; that can easily be determined from logs.

I think the default timeout on backends connection may be a little
short, though.

> > (3) Feature request: Request hashing.  It would be really cool if
> > Varnish were able to select the origin server (in reality another
> > Varnish proxy) by hashing the Request URI.  Having this ability would
> > improve the cache hit ratio overall where a pool of caching proxies is
> > used.
> We have sort of given up on the peer-to-peer cache fetches using
> dedicated protocols, but if you are able to tell that another
> varnish is a better place to pick up something, nothing prevents
> you from making that a backend of this varnish and doing
> a pass on the request.

No, I think what he means is selecting the backend based on client-ip
modulo number-of-backends so each client always gets the same backend
(which makes session tracking much easier)

Dag-Erling Smørgrav
Senior Software Developer
Linpro AS - www.linpro.no

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