Re: Thread implementations...
Erik Corry (ec@sign-tronic.dk)
Thu, 25 Jun 1998 17:16:06 +0200
On Thu, Jun 25, 1998 at 11:05:25AM -0400, Amsden, Zachary wrote:
> Erik Corry wrote
>> Possibly. But according to Squid's own doc, the primary problems
>> in Squid performance are
>>
>> 1) Not enough memory
>> 2) Too slow disks
>>
>> which as far as I can see aren't helped by sendfile. They also
>> say "CPU limitations are rarely encountered except in very large
>> caches". The same doc describes how to use clusters for large
>> caches.
>
> But too slow disks and not enough memory are directly
> related problems. If the kernel has frequently used
> disk files in the buffer cache, it still needs to copy
> the data to the user space server, then copy it back
> out onto a socket. With sendfile(), it can directly
> send data from the buffer cache without any user space
> involvement. In addition, we no longer need user
> space buffers in the server, cutting down on useless
> "memory duplication", allowing for more buffer cache.
Improvements to mmap, etc. could theoretically achieve this
without API changes. The question is whether such changes
would be too CPU-heavy and/or difficult to make use of in the
user-space server programs.
--
Erik Corry
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