Date: Sat, 17 Jan 2004 02:35:41 +0200 From: Ruslan Ermilov <ru@freebsd.org> To: Sten Daniel S?rsdal <sten.daniel.sorsdal@wan.no> Cc: freebsd-net@freebsd.org Subject: Re: ip_input - chksum - why is it done so early in ip_input? Message-ID: <20040117003541.GE9410@FreeBSD.org.ua> In-Reply-To: <0AF1BBDF1218F14E9B4CCE414744E70F5D97FF@exchange.wanglobal.net> References: <0AF1BBDF1218F14E9B4CCE414744E70F5D97FF@exchange.wanglobal.net>
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[-- Attachment #1 --] On Sat, Jan 17, 2004 at 12:50:04AM +0100, Sten Daniel S?rsdal wrote: > > Apologies for the cross-post, i wasnt sure if this was hackers or net material. > > I've often wondered why ip checksumming is done on every incoming > packet and not only on the packets that need to be delivered locally. > It looks like a very expensive way of doing it, especially on high > PPS. Basically all hosts do checksumming so why not just pass the bad > packet on, making the forward process alot cheaper (cpu wise)? > > I ran some tests (unable to disclose results) by removing it completely > and it seems to make a noticable impact on the performance. > Especially on for example gaming services where there is a high PPS versus > actual data. > > Besides that i'd like to add that FreeBSD has the fastest forwarding engine > i've seen on any free OS. It's in my opinion a very suitable OS for > routing/forwarding. > Have you tried ``sysctl net.inet.ip.fastforwarding=1''? It's documented in the inet(4) manpage. Cheers, -- Ruslan Ermilov FreeBSD committer ru@FreeBSD.org [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFACINdUkv4P6juNwoRAhHyAJ0ZfQo7YSJ/xababxfCHJWvHxh1MQCdHG5N V+1gNTE7l1R0Q5nCVNAKUB0= =7MK9 -----END PGP SIGNATURE-----
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