Date: Sun, 25 Aug 2002 17:05:57 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: Martin Heinen <martin@sumuk.de> Cc: "Ritz, Bruno" <bruno_ritz@gmx.ch>, FreeBSD-doc@FreeBSD.org Subject: Re: possible millisecond - microsecond confusion Message-ID: <20020825140556.GF762@hades.hell.gr> In-Reply-To: <20020825125050.A6559@sumuk.de> References: <GNENKHPCNMLFKGMPLJONCEMACCAA.bruno_ritz@gmx.ch> <20020825125050.A6559@sumuk.de>
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On 2002-08-25 12:50 +0000, Martin Heinen wrote: > On Sun, Aug 25, 2002 at 12:52:31AM +0200, Ritz, Bruno wrote: > > it's nothing dramatically but i think there is a little mistake in > > the freebsd 4.6.2 handbook. at bottom of page 226 and on top of > > page 227 (10.7.7 IPFW Overhead and Optimization) where the times > > packet processing times are written, the times are specified once > > as milliseconds (ms) another time as microseconds. > > > > The per-packet processing overhead in the former case was > > approximately 2.703ms/packet, or roughly 2.7 microseconds per > > rule > > Indeed, it seems strange to use ms and microseconds in the same > sentence. How about the attached patch, which changes microseconds > to ?s? Actually, it's probably "milliseconds" you want to keep. Microseconds seems like a very small amount of time for processing a packet. I could be wrong, though. If you want to change it to microseconds, you'd also have to update numbers like "370 packets per second". > Index: chapter.sgml > =================================================================== > RCS file: /u/cvs/doc/en_US.ISO8859-1/books/handbook/security/chapter.sgml,v > retrieving revision 1.114 > diff -u -r1.114 chapter.sgml > --- chapter.sgml 18 Aug 2002 17:22:15 -0000 1.114 > +++ chapter.sgml 25 Aug 2002 10:37:31 -0000 > @@ -2682,14 +2682,14 @@ > any</literal>.</para> > > <para>The per-packet processing overhead in the former case was > - approximately 2.703ms/packet, or roughly 2.7 microseconds per > + approximately 2.703ms/packet, or roughly 2.7 µs per > rule. Thus the theoretical packet processing limit with these > rules is around 370 packets per second. Assuming 10Mbps > Ethernet and a ~1500 byte packet size, we would only be able > to achieve a 55.5% bandwidth utilization.</para> > > <para>For the latter case each packet was processed in > - approximately 1.172ms, or roughly 1.2 microseconds per rule. > + approximately 1.172ms, or roughly 1.2 µs per rule. > The theoretical packet processing limit here would be about > 853 packets per second, which could consume 10Mbps Ethernet > bandwidth.</para> -- FreeBSD: The Power to Serve <> http://www.FreeBSD.org FreeBSD 5.0-CURRENT #0: Wed Aug 21 22:08:19 EEST 2002 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-doc" in the body of the message
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