> -----Original Message----- > From: Michael S. Tsirkin [mailto:[email protected]] > Sent: Friday, April 20, 2018 1:01 AM > To: Liang, Cunming <[email protected]> > Cc: Paolo Bonzini <[email protected]>; Bie, Tiwei <[email protected]>; > [email protected]; [email protected]; [email protected]; > [email protected]; [email protected]; Daly, Dan > <[email protected]>; Tan, Jianfeng <[email protected]>; Wang, Zhihong > <[email protected]>; Wang, Xiao W <[email protected]> > Subject: Re: [PATCH v3 6/6] vhost-user: support registering external host > notifiers > > On Thu, Apr 19, 2018 at 04:52:20PM +0000, Liang, Cunming wrote: > > > > > > > -----Original Message----- > > > From: Paolo Bonzini [mailto:[email protected]] > > > Sent: Thursday, April 19, 2018 11:52 PM > > > To: Michael S. Tsirkin <[email protected]>; Liang, Cunming > > > <[email protected]> > > > Cc: Bie, Tiwei <[email protected]>; [email protected]; > > > [email protected]; [email protected]; > > > [email protected]; [email protected]; Daly, Dan > > > <[email protected]>; Tan, Jianfeng <[email protected]>; Wang, > > > Zhihong <[email protected]>; Wang, Xiao W > > > <[email protected]> > > > Subject: Re: [PATCH v3 6/6] vhost-user: support registering external > > > host notifiers > > > > > > On 19/04/2018 17:42, Michael S. Tsirkin wrote: > > > >> A compiler barrier is enough on strongly-ordered memory platform. > > > >> As it doesn't re-order store, PCI device won't see a stale index > > > >> value. But a weakly-ordered memory needs sfence. > > > > > > > > Oh you are right. > > > > > > > > So it's only needed for non-intel platforms or when packets are in > > > > WC memory then. And I don't know whether dpdk ever puts packets in > > > > WC memory. > > > > > > > > I guess we'll cross this bridge when we get to it. > > > > > > Non-TSO architectures seem important... > > > > I'm not familiar with Non-TSO, trying to understand the difference > > according to the feature set. Let's say non-TSO architectures do not > > set 'weak_barriers'. Then mandatory barrier is used for software. HW > > offload on that platform would choose different feature set against > > software? > > Right. We'll need a flag for this feature for starters. It doesn't exist > :) Paolo also points out that we should then add code to disallow migration > between setups with and without the feature. I see. Thanks.
> > > If it's not, essentially we're worried about live migration from a TSO to a > > non- > TSO architectures platform? > > Probably not. > > > > > > > Paolo --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
