Date: Fri, 22 Oct 1999 19:31:59 +0100 (MET) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: rminnich@lanl.gov (Ronald G. Minnich) Cc: hackers@FreeBSD.ORG Subject: Re: profile of tcp Message-ID: <199910221831.TAA02285@labinfo.iet.unipi.it> In-Reply-To: <Pine.SGI.4.10.9910211451470.269517-100000@acl.lanl.gov> from "Ronald G. Minnich" at Oct 21, 99 02:53:47 pm
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> I'm wondering if anyone in this group has done or knows of a good profile > of a tcp send going from user mode to bits on the wire. Reason I'm asking > is the old "put TCP/IP on the NIC" is once again rearing its head, and I'm > hoping there are numbers I can point to (ones that aren't old, that is) > about why this may not be the best idea in the world. FreeBSD seems a good > choice since it has a pretty reasonable implementation. one of the main motivations for _not_ having TCP on the NIC is that you won't see the same progress in performance for NICs as you see for general purpose CPUs. Or, maybe it is more correct to say that you might see a more coarse-grained progress so the NIC speed might be 1-2 yrs behind the state of art in CPUs, thus any gain in having the protocol implemented in hardware (actually microcode, i think) is probably eaten by this lag. Also there is the usual lack of flexibility in having things done in hw/microcode vs. software. And finally, i think having the proto in the NIC may be useful for maybe a router or a box doing traffic switching, but for things like a web server or a cache you also have to look at optimizing the datapath between disk and the NIC. cheers luigi -----------------------------------+------------------------------------- Luigi RIZZO, luigi@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL/FAX: +39-050-568.533/522 . via Diotisalvi 2, 56126 PISA (Italy) http://www.iet.unipi.it/~luigi/ngc99/ ==== First International Workshop on Networked Group Communication ==== -----------------------------------+------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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