[PATCH v3 5/5] vhost_user: Increase number of memory regions

[Bathija, Pravin]

Responses inline.


Internal Use - Confidential
> -----Original Message-----
> From: fengchengwen <fengchengwen at huawei.com>
> Sent: Tuesday, November 4, 2025 12:12 AM
> To: Bathija, Pravin <Pravin.Bathija at dell.com>; dev at dpdk.org
> Cc: pravin.m.bathija.dev at gmail.com
> Subject: Re: [PATCH v3 5/5] vhost_user: Increase number of memory regions
>
>
> [EXTERNAL EMAIL]
>
> On 11/4/2025 12:21 PM, Pravin M Bathija wrote:
> > In this patch the number of memory regions are increased from
> > 8 to 128. When a vhost-user front-end such as qemu or libblkio queries
> > the back-end such as dpdk with the message, get max number of memory
> > slots, the back-end replies with this number 128 instead of the
> > previously defined 8. The back-end also allocates that many slots in
> > the memory table where regions are added/removed as requested by the
> > vhost-user front-end. This also helps the vhost- user front-end to
> > limit the number of memory regions when sending the set mem table
> > message ar adding memory regions.
> >
> > Signed-off-by: Pravin M Bathija <pravin.bathija at dell.com>
> > ---
> >  lib/vhost/vhost_user.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/lib/vhost/vhost_user.h b/lib/vhost/vhost_user.h index
> > 5a0e747b58..c6ad5b76d6 100644
> > --- a/lib/vhost/vhost_user.h
> > +++ b/lib/vhost/vhost_user.h
> > @@ -11,7 +11,7 @@
> >
> >  /* refer to hw/virtio/vhost-user.c */
> >
> > -#define VHOST_MEMORY_MAX_NREGIONS 8
> > +#define VHOST_MEMORY_MAX_NREGIONS 128
>
> The address translation may increase a lot if the real region is 128.
> Maybe we should add another patch to optimize it.

Could you please share more thoughts on this ?  Are you concerned about the number of addresses and translation table bloat ? What optimization are you suggesting ?

>
> >
> >  #define VHOST_USER_NET_SUPPORTED_FEATURES \
> >     (VIRTIO_NET_SUPPORTED_FEATURES | \