From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: AlacrityVM benchmark numbers updated Date: Wed, 26 Aug 2009 14:42:53 -0400 Message-ID: <4A95822D.9060207@gmail.com> References: <4A948962.7090909@gmail.com> <4A950B75.5020409@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigFC6960BF101ED27437A67DF7" Cc: alacrityvm-devel@lists.sourceforge.net, "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "Michael S. Tsirkin" , netdev@vger.kernel.org To: Avi Kivity Return-path: In-Reply-To: <4A950B75.5020409@redhat.com> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigFC6960BF101ED27437A67DF7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Avi Kivity wrote: > On 08/26/2009 04:01 AM, Gregory Haskins wrote: >> We are pleased to announce the availability of the latest networking >> benchmark numbers for AlacrityVM. We've made several tweaks to the >> original v0.1 release to improve performance. The most notable is a >> switch from get_user_pages to switch_mm+copy_[to/from]_user thanks to = a >> review suggestion from Michael Tsirkin (as well as his patch to >> implement it). >> >> This change alone accounted for freeing up an additional 1.2Gbps, whic= h >> is over 25% improvement from v0.1. The previous numbers were 4560Gbps= >> before the change, and 5708Gbps after (for 1500mtu over 10GE). This >> moves us ever closer to the goal of native performance under >> virtualization. >> =20 >=20 > Interesting, it's good to see that copy_*_user() works so well. Note > that there's a possible optimization that goes in the opposite directio= n > - keep using get_user_pages(), but use the dma engine API to perform th= e > actual copy. I expect that it will only be a win when using tso to > transfer full pages. Large pages may also help. >=20 > Copyless tx also wants get_user_pages(). It makes sense to check if > switch_mm() + get_user_pages_fast() gives better performance than > get_user_pages(). Actually, I have already look at this and it does indeed seem better to use switch_mm+gupf() over gup() by quite a large margin. You could then couple that with your DMA-engine idea to potentially gain even more benefits (though probably not for networking since most NICs have their own DMA engine anyway). Kind Regards, -Greg --------------enigFC6960BF101ED27437A67DF7 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkqVgi0ACgkQP5K2CMvXmqF9nwCfWf6IPAu7kF78fVbsgoaFUjSp Cd4AnjZvSHEZuOtd8qhOXStUi2sALT19 =LNc6 -----END PGP SIGNATURE----- --------------enigFC6960BF101ED27437A67DF7--