From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: [RFC PATCH 00/17] virtual-bus Date: Thu, 02 Apr 2009 08:30:47 -0400 Message-ID: <49D4AFF7.1050603@novell.com> References: <20090402085253.GA29932@gondor.apana.org.au> <49D47F11.6070400@redhat.com> <20090402091639.GA30126@gondor.apana.org.au> <49D484F5.2000400@redhat.com> <20090402092936.GA30333@gondor.apana.org.au> <49D487A6.407@redhat.com> <49D49C1F.6030306@novell.com> <49D4A89E.5090407@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigE0BFBB5CBC84E288E51B5F0F" Cc: Herbert Xu , anthony@codemonkey.ws, andi@firstfloor.org, linux-kernel@vger.kernel.org, agraf@suse.de, pmullaney@novell.com, pmorreale@novell.com, rusty@rustcorp.com.au, netdev@vger.kernel.org, kvm@vger.kernel.org, Mark McLoughlin To: Avi Kivity Return-path: Received: from victor.provo.novell.com ([137.65.250.26]:51013 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063AbZDBM2c (ORCPT ); Thu, 2 Apr 2009 08:28:32 -0400 In-Reply-To: <49D4A89E.5090407@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigE0BFBB5CBC84E288E51B5F0F Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Avi Kivity wrote: > Gregory Haskins wrote: > > =20 > >>> Why does a kernel solution not need to know when a packet is >>> transmitted? >>> >>> =20 >> >> You do not need to know when the packet is copied (which I currently >> do). You only need it for zero-copy (of which I would like to support= , >> but as I understand it there are problems with the reliability of prop= er >> callback (i.e. skb->destructor). >> >> Its "fire and forget" :) >> =20 > > It's more of a "schedule and forget" which I think brings you the > win. The host disables notifications and schedules the actual tx work > (rx from the host's perspective). So now the guest and host continue > producing and consuming packets in parallel. So long as the guest is > faster (due to the host being throttled?), notifications continue to > be disabled. Yep, when the "producer::consumer" ratio is > 1, we mitigate signaling.=20 When its < 1, we signal roughly once per packet. > > If you changed your rx_isr() to process the packets immediately > instead of scheduling, I think throughput would drop dramatically. Right, that is the point. :) This is that "soft asic" thing I was talking about yesterday. -Greg --------------enigE0BFBB5CBC84E288E51B5F0F Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAknUr/gACgkQlOSOBdgZUxl/+gCePKyvShVBT4++tDDPh+Sfe81t QYwAn1FzLp21E/D6vvcHDQVVKnv1o3VQ =Z49L -----END PGP SIGNATURE----- --------------enigE0BFBB5CBC84E288E51B5F0F--