Varnish use for purely binary files

Michael S. Fischer michael at
Tue Jan 19 01:45:57 CET 2010

On Jan 18, 2010, at 4:35 PM, Poul-Henning Kamp wrote:

> In message <97F066DD-4044-46A7-B3E1-34CE928E81F3 at>, Ken Brownfield wri
> tes:
>> Ironically and IMHO, one of the barriers to Varnish scalability
>> is its thread model, though this problem strikes in the thousands
>> of connections.
> It's only a matter of work to pool slow clients in Varnish into
> eventdriven writer clusters, but so far I have not seen a
> credible argument for doing it.
> A thread is pretty cheap to have around if it doesn't do anything,
> and the varnish threads typically do not do anything during the
> delivery-phase:  They are stuck in the kernel in a writev(2) 
> or sendfile(2) system call.

Does Varnish already try to utilize CPU caches efficiently by employing some sort of LIFO thread reuse policy or by pinning thread pools to specific CPUs?  If not, there might be some opportunity for optimization there.


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