netdev - Re: thoughts stac/clac and get user for vhost

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 26 Dec 2018 12:03:50 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     netdev@...r.kernel.org
Subject: Re: thoughts stac/clac and get user for vhost

On 2018/12/26 上午12:41, Michael S. Tsirkin wrote:
> Hi!
> I was just wondering: packed ring batches things naturally.
> E.g.
>
> user_access_begin
> check descriptor valid
> smp_rmb
> copy descriptor
> user_access_end

But without speculation on the descriptor (which may only work for 
in-order or even a violation of spec). Only one two access of a single 
descriptor could be batched. For split ring, we can batch more since we 
know how many descriptors is pending. (avail_idx - last_avail_idx).

Anything I miss?

Thanks

>
> So packed layout should show the gain with this approach.
> That could be motivation enough to finally enable vhost packed ring
> support.
>
> Thoughts?
>