From: "Michael S. Tsirkin" <mst@redhat.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jason Wang <jasowang@redhat.com>,
kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 3/3] vhost: access vq metadata through kernel virtual address
Date: Thu, 13 Dec 2018 16:58:04 -0500 [thread overview]
Message-ID: <20181213165731-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20181213211840.GC18692@char.us.oracle.com>
On Thu, Dec 13, 2018 at 04:18:40PM -0500, Konrad Rzeszutek Wilk wrote:
> .giant snip..
> > > + npinned = get_user_pages_fast(uaddr, npages, write, pages);
> > > + if (npinned != npages)
> > > + goto err;
> > > +
> >
> > As I said I have doubts about the whole approach, but this
> > implementation in particular isn't a good idea
> > as it keeps the page around forever.
> > So no THP, no NUMA rebalancing, userspace-controlled
> > amount of memory locked up and not accounted for.
> >
> > Don't get me wrong it's a great patch in an ideal world.
> > But then in an ideal world no barriers smap etc are necessary at all.
>
> So .. suggestions on how this could be accepted? As in other ways
> where we still get vmap and the issues you mentioned are not troubling you?
>
> Thanks!
I'd suggest leave vmap alone and find ways to speed up accesses
that can fault.
--
MST
next prev parent reply other threads:[~2018-12-13 21:58 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 10:10 [PATCH net-next 0/3] vhost: accelerate metadata access through vmap() Jason Wang
2018-12-13 10:10 ` [PATCH net-next 1/3] vhost: generalize adding used elem Jason Wang
2018-12-13 19:41 ` Michael S. Tsirkin
2018-12-14 4:00 ` Jason Wang
2018-12-13 10:10 ` [PATCH net-next 2/3] vhost: fine grain userspace memory accessors Jason Wang
2018-12-13 10:10 ` [PATCH net-next 3/3] vhost: access vq metadata through kernel virtual address Jason Wang
2018-12-13 15:44 ` Michael S. Tsirkin
2018-12-13 21:18 ` Konrad Rzeszutek Wilk
2018-12-13 21:58 ` Michael S. Tsirkin [this message]
2018-12-14 3:57 ` Jason Wang
2018-12-14 12:36 ` Michael S. Tsirkin
2018-12-24 7:53 ` Jason Wang
2018-12-24 18:10 ` Michael S. Tsirkin
2018-12-25 10:05 ` Jason Wang
2018-12-25 12:50 ` Michael S. Tsirkin
2018-12-26 3:57 ` Jason Wang
2018-12-26 15:02 ` Michael S. Tsirkin
2018-12-27 9:39 ` Jason Wang
2018-12-30 18:30 ` Michael S. Tsirkin
2019-01-02 11:38 ` Jason Wang
2018-12-15 21:15 ` David Miller
2018-12-14 14:48 ` kbuild test robot
2018-12-13 15:27 ` [PATCH net-next 0/3] vhost: accelerate metadata access through vmap() Michael S. Tsirkin
2018-12-14 3:42 ` Jason Wang
2018-12-14 12:33 ` Michael S. Tsirkin
2018-12-14 15:31 ` Michael S. Tsirkin
2018-12-24 8:32 ` Jason Wang
2018-12-24 18:12 ` Michael S. Tsirkin
2018-12-25 10:09 ` Jason Wang
2018-12-25 12:52 ` Michael S. Tsirkin
2018-12-26 3:59 ` Jason Wang
2018-12-13 20:12 ` Michael S. Tsirkin
2018-12-14 4:29 ` Jason Wang
2018-12-14 12:52 ` Michael S. Tsirkin
2018-12-15 19:43 ` David Miller
2018-12-16 19:57 ` Michael S. Tsirkin
2018-12-24 8:44 ` Jason Wang
2018-12-24 19:09 ` Michael S. Tsirkin
2018-12-14 15:16 ` Michael S. Tsirkin
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