Re: [squid-users] TCP send/receive buffer tuning

On 31.01.2011 23:53, Amos Jeffries wrote:
> On Mon, 31 Jan 2011 10:57:57 +0100, "Jack Falworth"<jackf.mail_at_gmx.de>
> wrote:
>> Hi squid-users,
>>
>> I have a question regarding the TCP send/receive buffer size Squid uses.
>> For my high-performance setup I increased both buffer sizes on my Ubuntu
>> 10.04 system. Unfortunately I found out that Squid 2.7 (as well as 3.x)
>> limits the receive buffer to 64K and the send buffer to 32K in the
>> configure.in script.
>>
>> In addition I found this bug report regarding this check:
>> http://bugs.squid-cache.org/show_bug.cgi?id=1075
>>
>> I couldn't really figure out the problem with Squid using higher buffer
>> sizes if it is the intention of the administrator to increase those
> values.
>> This check was included in CVS rev. 1.303 back in 2005, thus it's quite
>> old.
>>
>> Is this some legacy check or is it still important with today's systems?
>> Can I safely remove this check or will this have some side-effects, e.g.
>> say the some internal data structures won't be able to cope with higher
>> values?
> Note that setting ONLY affects the TCP buffers so 64K worth of packets can
> sit outside of Squid in the networking stack.
> This has side-effects on the ACK packets. While they are waiting in that
> buffer they are possibly ACKed but not actually received by Squid. If
> anything causes Squid to stop, crash or slow down on its read()'s and
> accept()'s the client can be left with incorrect information about the
> state of those bytes.
>
But this could also happen on a 64K buffer. If Squid crashes or goes
down for some reason then information is lost anyways.
Thus the only reason increasing the buffer size in a high-traffic
scenario would be a bad idea is if Squid is somehow overloaded and
slowed down on its read()'s and accept()'s? But if I make sure that
Squid can handle some peak traffic values without being overloaded it
would be safe to increase buffer sizes?
Received on Tue Feb 01 2011 - 13:31:25 MST