Varnish caching issues, cache size, expires, cache resets, whatsgoing on?

[Brian Smith]

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