Varnish caching issues, cache size, expires, cache resets, whatsgoing on?
Brian Smith
brian at briansmith.org
Sat May 10 18:54:08 CEST 2008
Demitrious Kelly wrote:
> Also, interestingly, the response is higher than our other server (we
> have two handling a split load, what I detailed was just one of them,
> the other is left alone while we tweak this one.) A 1x1 pixel image
> request coming from the original (which crashes all the time) gets sent
> in 0.08x seconds, and this one with tcmalloc in 0.11x seconds. I
> definitely consider 0.03 seconds a price worth stability, but its an
> interesting observation nonetheless
Maybe the operating system if trying to proactively write pages to swap in
the background. You might be able to tune the configuration to reduce or
stop that behavior if the whole working set is supposed to fit in memory.
Or, you could increase the expiration times so that the cache is larger than
8GB, and see if you can use the pre-swapping to your benefit. The difference
between a cache hit and a cache miss is probably much larger than 0.03
seconds.
Regards,
Brian
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