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Re: [Qemu-devel] [PATCH 0/2] vhost: two fixes
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] vhost: two fixes |
Date: |
Fri, 15 Dec 2017 06:36:21 +0200 |
On Fri, Dec 15, 2017 at 02:38:35AM +0000, Zhoujian (jay) wrote:
> Hi Dave,
>
> > -----Original Message-----
> > From: Dr. David Alan Gilbert [mailto:address@hidden
> > Sent: Friday, December 15, 2017 3:49 AM
> > To: Michael S. Tsirkin <address@hidden>
> > Cc: Zhoujian (jay) <address@hidden>; address@hidden;
> > Huangweidong (C) <address@hidden>; Gonglei (Arei)
> > <address@hidden>; wangxin (U) <address@hidden>;
> > Liuzhe (Cloud Open Labs, NFV) <address@hidden>; Igor Mammedov
> > <address@hidden>
> > Subject: Re: [PATCH 0/2] vhost: two fixes
> >
> > * Michael S. Tsirkin (address@hidden) wrote:
> > > On Fri, Dec 15, 2017 at 12:36:30AM +0800, Jay Zhou wrote:
> > > > Jay Zhou (2):
> > > > vhost: add used memslot number for vhost-user
> > > > vhost: double check memslot number
> > > >
> > > > hw/virtio/vhost-user.c | 31 +++++++++++++++++++++++++
> > > > hw/virtio/vhost.c | 49
> > ++++++++++++++++++++++++++++++++++-----
> > > > include/hw/virtio/vhost-backend.h | 4 ++++
> > > > 3 files changed, 78 insertions(+), 6 deletions(-)
> > >
> > > Cc two developers working on these files right now.
> >
> > I have to admit to not understanding the 'used_memslots' variable.
> >
> > * It's a global in vhost.c
> > * but set by vhost_set_memory that's called from the listener associated
> > with each individual vhost
> > * While they're probably always the same, the merging code calls
> > the vhost_backend_can_merge method for each device, so the number
> > of regions can be different.
> >
>
> Your mean for some devices the new added MemoryRegionSection can be merged,
> but for others it can not be merged? IIUC the vhost_mem for each vhost_dev
> is the same.
>
> Meanwhile, I think it is more reasonable to add globals in vhost-backend.c
> and vhost-user.c respectively instead of 'used_memslots'. The reason
> is explained in patch 1. What do you think?
>
> Regards,
> Jay
I'd rather avoid globals completely if possible.
--
MST