Date: Sun, 21 Jan 2007 20:32:58 +0100 From: Max Laier <max@love2party.net> To: Bruce Evans <bde@zeta.org.au> Cc: freebsd-net@freebsd.org Subject: Re: slow writes on nfs with bge devices Message-ID: <200701212033.34914.max@love2party.net> In-Reply-To: <20070121215054.C24780@delplex.bde.org> References: <20070121155510.C23922@delplex.bde.org> <200701210809.27770.max@love2party.net> <20070121215054.C24780@delplex.bde.org>
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--nextPart1595927.pzSa1nX3oL Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Sunday 21 January 2007 13:25, Bruce Evans wrote: > On Sun, 21 Jan 2007, Max Laier wrote: > > On Sunday 21 January 2007 07:25, Bruce Evans wrote: > >> nfs writes much less well with bge NICs than with other NICs (sk, > >> fxp, > > > > Do you use hardware checksumming on the bge? There is an XXX in > > bge_start_locked() that looks a bit suspicious to me. > > I use the default for that. Wouldn't checksum problems show up as > errors somwhere? Did you look at the code in question? It is concerned with fragmented=20 packet chains (which NFS over UDP usually generated) and only commits to=20 sending them, if there are enough descriptors available at once. This=20 can easily explain burstyness. Can you just try to disable the delayed checksums via "ifconfig -txcsum"? = =20 Should be an easy enough test. > >>> [excessive quoting deleted] > > tcpdump shows a lot of intervals between nfs write requests of almost > exactly 10 mS (even with HZ =3D 1000, but more obvious with HZ =3D 100) > for the broken case, so the problem is apparently related to timeouts, > or timeouts are masking a larger problem. (The average interval > between write requests needs to be about 683 uS to avoid wasting any > bandwith. fxp <-> fxp on the same network averages 708 uS. fxp <-> bge > 5701 averages 3981.) See above, I really think that there is something about that if_start loop= =20 that might be causing this. =2D-=20 /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News --nextPart1595927.pzSa1nX3oL Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQBFs8AOXyyEoT62BG0RAhh5AJ9gf9+sPSC4Eur4cxo3Qnm1xPGmFgCdFZn7 yecaaZcGElSbDiPS6zx3USA= =4wpX -----END PGP SIGNATURE----- --nextPart1595927.pzSa1nX3oL--
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