Date: Fri, 31 Jul 1998 15:54:44 -0700 From: Mike Smith <mike@smith.net.au> To: Craig Spannring <cts@internetcds.com> Cc: chanders@timing.com (Craig Anderson), freebsd-hackers@FreeBSD.ORG Subject: Re: Using FreeBSD for data acquisition? (long) Message-ID: <199807312254.PAA01058@dingo.cdrom.com> In-Reply-To: Your message of "Fri, 31 Jul 1998 13:59:56 PDT." <199807312059.NAA18156@bangkok.office.cdsnet.net>
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> > That pretty much matches what I'm seeing for a server I'm writing. > My server must respond in less than 3 seconds. Normally it is able > to respond in a millisecond or two, but occasionally it takes around > 1000 milliseconds. > > I've duplicated the problem occurring even under real time priority > with no other processes on the machine except for init, pagedaemon, > vmdaemon, update, and one csh. I had virtual memory disabled to > eliminate any paging activity. If you're doing this over the net, it looks like you're seeing the TCP slow-start. Try turning it off; it makes a huge difference. 8) > I tracked the problem down to the fact that I'm not getting any CPU > time for a substantial (at least up to 500 milliseconds) amount of > time even though I'm using rtprio and there is nothing else that > should be running. So what is running? > In regards to your question of why 0.100 seconds is so common, FreeBSD > uses a 10msec quantum. I suspect if you change kern.quantum to some > other value then the other value will become more common. 0.1s != 10msec. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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