does varnish write objects to disk?

Poul-Henning Kamp phk at
Mon Jan 15 19:33:29 CET 2007

In message <45ABC845.8010202 at>, Flemming Frandsen writes:
>Poul-Henning Kamp wrote:
>>>Varnish caches objects into *memory* and not disk right?
>> No, varnish caches objects into "virtual memory" which means that
>> RAM acts as a cache for the disk.
>I guess the interesting detail is how eager the kernel is to write the 
>mapped memory to disk.
>It would be a shame to spend time and IO bandwidth to write a 1G cache 
>out to disk if the box has 4G of RAM and would never need the RAM for 
>anything other than the cache, woudn't it?

The kernels I know of can be described as distinctively reluctant
to write things out.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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