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From "Jeffrey W. Baker" <>
Subject Re: MMAP support for APR
Date Fri, 15 Oct 1999 02:09:47 GMT
Tony Finch wrote:
> I'm going to mention Flash again because it's cool.
> This server does some really cool things with mmap: It maintains a
> cache of chunks of mmapped files that is tuned to the available memory
> in the machine and has an LRU replacement strategy to approximate the
> kernel's page replacement strategy. It uses auxiliary processes to
> peek at the pages of the mmap (and therefore block while they are read
> in) so that the main server doesn't block. If Dean's idea of a
> select-loop-based MPM happens then this could be very handy (even if
> the select loop is hidden inside some userland threading library).
> There are some other optimisations: Instead of cacheing struct stats,
> it caches the translation of URI to filename. It's based on thttpd so
> it doesn't have to worry about .htaccess files, but I like the idea of
> being able to avoid traipsing around the filesystem on every request.
> It also caches response headers so that they can be re-used, and does
> some tricks to avoid realignment costs inside the network stack.

Isn't that last paragraph substantially the same as the last of the "10x
performance increase" patches send by SGI?  I believe it cached URI
translations and repsonse headers for static content within the
framework of the current mod_mmap_static.


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