netdev - Re: [RFC PATCH v2 03/14] xsk: add umem fill queue support and mmap

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Message-ID: <20180412170110-mutt-send-email-mst@kernel.org>
Date:   Thu, 12 Apr 2018 17:04:55 +0300
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     "Karlsson, Magnus" <magnus.karlsson@...el.com>
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        "Duyck, Alexander H" <alexander.h.duyck@...el.com>,
        "alexander.duyck@...il.com" <alexander.duyck@...il.com>,
        "john.fastabend@...il.com" <john.fastabend@...il.com>,
        "ast@...com" <ast@...com>, "brouer@...hat.com" <brouer@...hat.com>,
        "willemdebruijn.kernel@...il.com" <willemdebruijn.kernel@...il.com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "michael.lundkvist@...csson.com" <michael.lundkvist@...csson.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Singhai, Anjali" <anjali.singhai@...el.com>,
        "Zhang, Qi Z" <qi.z.zhang@...el.com>,
        "ravineet.singh@...csson.com" <ravineet.singh@...csson.com>
Subject: Re: [RFC PATCH v2 03/14] xsk: add umem fill queue support and mmap

On Thu, Apr 12, 2018 at 07:38:25AM +0000, Karlsson, Magnus wrote:
> I think you are definitely right in that there are ways in which
> we can improve performance here. That said, the current queue
> performs slightly better than the previous one we had that was
> more or less a copy of one of your first virtio 1.1 proposals
> from little over a year ago. It had bidirectional queues and a
> valid flag in the descriptor itself. The reason we abandoned this
> was not poor performance (it was good), but a need to go to
> unidirectional queues. Maybe I should have only changed that
> aspect and kept the valid flag.

Is there a summary about unidirectional queues anywhere?  I'm curious to
know whether there are any lessons here to be learned for virtio
or ptr_ring.

-- 
MST