From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Courtier-Dutton Subject: Re: [PATCH] Add I/O hypercalls for i386 paravirt Date: Wed, 22 Aug 2007 23:15:11 +0100 Message-ID: <46CCB56F.8090308@superbug.co.uk> References: <46CBC842.4070100@vmware.com> <46CCB088.8070606@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <46CCB088.8070606@goop.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jeremy Fitzhardinge Cc: Andrew Morton , Linux Kernel Mailing List , Chris Wright , Virtualization Mailing List List-Id: virtualization@lists.linuxfoundation.org Jeremy Fitzhardinge wrote: > Zachary Amsden wrote: >> This patch provides hypercalls for the i386 port I/O instructions, >> which vastly helps guests which use native-style drivers. For certain >> VMI workloads, this provides a performance boost of up to 30%. We >> expect KVM and lguest to be able to achieve similar gains on I/O >> intensive workloads. > > Two comments: > > - I should dust off my "break up paravirt_ops" patch, and this would fit > nicely into it (I think we already discussed this) > > - What happens if you *don't* want to pv some of the io instructions? > What if you have a device which is directly exposed to the guest? If one could directly expose a device to the guest, this feature could be extremely useful for me. Is it possible? How would it manage to handle the DMA bus mastering? James