OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

virtio-dev message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


Subject: RE: [PATCH v3 6/6] vhost-user: support registering external host notifiers



> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> Sent: Thursday, April 19, 2018 11:52 PM
> To: Michael S. Tsirkin <mst@redhat.com>; Liang, Cunming
> <cunming.liang@intel.com>
> Cc: Bie, Tiwei <tiwei.bie@intel.com>; jasowang@redhat.com;
> alex.williamson@redhat.com; stefanha@redhat.com; qemu-devel@nongnu.org;
> virtio-dev@lists.oasis-open.org; Daly, Dan <dan.daly@intel.com>; Tan, Jianfeng
> <jianfeng.tan@intel.com>; Wang, Zhihong <zhihong.wang@intel.com>; Wang,
> Xiao W <xiao.w.wang@intel.com>
> 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? 
If it's not, essentially we're worried about live migration from a TSO to a non-TSO architectures platform?

> 
> Paolo


[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]