[squid-users] Subject: Bandwidth Ceiling

squid-cache at pixelrebel.com squid-cache at pixelrebel.com
Wed Jun 29 19:29:38 UTC 2016

Thanks for the tip Amos.  I tried compiling my own version with BUFSIZ set to 32KB, but 
it didn't seem to help.  The TCP buffer size on my system is 212992 bytes, I tried
64KB too, but that also didn't improve my situation.  Aside from adjsting the 
read_ahead_gap, is there anything else I'm missing?  I'm sort of out of my league here
so I may just quit and wait for v4. ;)


>Sadly, that is kind of expected at present for any single client
>connection. We have some evidence that Squid is artificially lowering
>packet sizes in a few annoying ways. Used to make sense on slower
>networks, but not nowdays.
>Nathan Hoad has been putting a lot of work into this recently to figure
>out what can be done and has a performance fix in Squid-4. That is not
>going to make it into 3.5 because it relies on some major restructuring
>done only in Squid-4 code.
>But, if you are okay with playing around in the code his initial patch
>submission shows the key value to change:
>which should be the same in Squid-3. The 64KB bump in that patch leads
>to some pain so dont just apply that. In the end we went with 16KB to
>avoid huge per-connection memory requirements. It should really be tuned
>to about 1/2 or 1/4 the TCP buffer size on your system.
>After bumping up that read_ahead_gap directive also needs to be bumped
>up to a minimum of whatever value you choose there.

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