Date: Fri, 18 Oct 2002 10:38:25 -0700 From: Luigi Rizzo <rizzo@icir.org> To: Petri Helenius <pete@he.iki.fi> Cc: Jim McGrath <jimmcgra@bellatlantic.net>, Lars Eggert <larse@ISI.EDU>, freebsd-net@FreeBSD.ORG, freebsdnic@mailbox.cps.intel.com Subject: Re: ENOBUFS Message-ID: <20021018103825.B82982@carp.icir.org> In-Reply-To: <00b001c276ba$1533dbf0$3500080a@PHE>; from pete@he.iki.fi on Fri, Oct 18, 2002 at 06:21:37PM %2B0300 References: <NDBBKKEELKBCJJBEGDECCEHJCGAA.jimmcgra@bellatlantic.net> <00b001c276ba$1533dbf0$3500080a@PHE>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, Oct 18, 2002 at 06:21:37PM +0300, Petri Helenius wrote: ... > Luigi´s polling work would be useful here. That would lead to incorrect > timestamps > on the packets, though? polling introduce an extra uncertainty which might be as large as an entire clock tick, yes. But even with interrupts, you cannot trust the time when the interrupt driver is run -- there are cases where an ISR is delayed by 10ms or more. And even when it runs, it might take quite a bit of time (up to a few 100's of microseconds) to drain the receive queue from packets received earlier. in normal cases, timestamps are reasonably accurate in both cases. In special cases, the error induced by having interrupts blocked causes errors which are much larger than polling alone. cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20021018103825.B82982>