Date: Thu, 12 Nov 2009 18:08:35 -0800 From: Sean Hamilton <sh@bel.bc.ca> To: freebsd-hackers@freebsd.org Subject: NUMA support; tweaking TCP for GPRS Message-ID: <20091113020835.GE12442@visor.slugabed.org>
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Greetings -hackers, I have two unrelated questions. First, what is the status of NUMA support in FreeBSD? Is there a performance penalty on Nehalem-class systems, compared with Linux, which advertises NUMA awareness? Google seems to turn up very little on this subject. Second, I am using a FreeBSD server to talk to equipment which has a GPRS internet connection. This is fairly high latency (approximately one second RTT) and is prone to bursts of packet loss, or bursts of extremely high latency -- perhaps up to a minute. These intervals cause many retransmissions, which I presume is a good strategy over the internet, but not so good for GPRS. For my application, latency is mostly irrelevant. However, data over GPRS is very expensive, so I would like to reduce as much as possible the number of TCP retransmissions made on the FreeBSD side, possibly at the expense of latency. So, I am looking for suggestions on how to achieve this, via sysctl, setsockopt, etc. There seems to be a lot of literature regarding TCP tuning, but usually the focus is on improving performance, not reducing network traffic. The "rexmit_min" and "rexmit_sop" sysctls mentioned in tcp(4) seem interesting, but it's not clear to me exactly how they might be adjusted for this purpose. Thanks in advance, -- Sean Hamilton <sh@bel.bc.ca>
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