lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 15 Sep 2010 12:10:00 +0200 From: "Michael S. Tsirkin" <mst@...hat.com> To: Shirley Ma <mashirle@...ibm.com> Cc: Arnd Bergmann <arnd@...db.de>, Avi Kivity <avi@...hat.com>, "Xin, Xiaohui" <xiaohui.xin@...el.com>, David Miller <davem@...emloft.net>, netdev@...r.kernel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [RFC PATCH 2/2] macvtap: TX zero copy between guest and host kernel On Tue, Sep 14, 2010 at 11:21:15PM -0700, Shirley Ma wrote: > On Wed, 2010-09-15 at 07:12 +0200, Michael S. Tsirkin wrote: > > Yes, I agree this patch is useful for demo purposes: > > simple, and shows what kind of performance gains > > we can expect for TX. > > Any other issue you can see in this patch beside vhost descriptors > update? Another issue is that macvtap can be bound to almost anything, including e.g. a tap device or a bridge, which might hang on to skb fragments for unlimited time. Zero copy TX won't easily work there. I can imagine either somehow triggering a data copy after the fact (hard), or detecting such devices and avoiding zero copy (unfortunate for guest to guest, and drivers will need tuning). > Don't you think once I address vhost_add_used_and_signal update > issue, it is a simple and complete patch for macvtap TX zero copy? > > Thanks > Shirley I like the fact that the patch is simple. Unfortunately I suspect it'll stop being simple by the time it's complete :) -- MST -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists