netdev - Re: [PATCH net-next v4] xsk: support use vaddr as ring

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Date:   Fri, 17 Feb 2023 16:59:20 +0800
From:   Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
To:     Alexander Lobakin <aleksander.lobakin@...el.com>
Cc:     <netdev@...r.kernel.org>,
        Björn Töpel <bjorn@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        <bpf@...r.kernel.org>
Subject: Re: [PATCH net-next v4] xsk: support use vaddr as ring

On Thu, 16 Feb 2023 14:04:47 +0100, Alexander Lobakin <aleksander.lobakin@...el.com> wrote:
> From: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> Date: Thu, 16 Feb 2023 16:30:47 +0800
>
> > When we try to start AF_XDP on some machines with long running time, due
> > to the machine's memory fragmentation problem, there is no sufficient
> > contiguous physical memory that will cause the start failure.
> >
> > If the size of the queue is 8 * 1024, then the size of the desc[] is
> > 8 * 1024 * 8 = 16 * PAGE, but we also add struct xdp_ring size, so it is
> > 16page+. This is necessary to apply for a 4-order memory. If there are a
> > lot of queues, it is difficult to these machine with long running time.
> >
> > Here, that we actually waste 15 pages. 4-Order memory is 32 pages, but
> > we only use 17 pages.
> >
> > This patch replaces __get_free_pages() by vmalloc() to allocate memory
> > to solve these problems.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> > Acked-by: Magnus Karlsson <magnus.karlsson@...el.com>
> > ---
>
> [...]
>
> > diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
> > index c6fb6b763658..bfb2a7e50c26 100644
> > --- a/net/xdp/xsk_queue.h
> > +++ b/net/xdp/xsk_queue.h
> > @@ -45,6 +45,7 @@ struct xsk_queue {
> >  	struct xdp_ring *ring;
> >  	u64 invalid_descs;
> >  	u64 queue_empty_descs;
> > +	size_t ring_vmalloc_size;
>
> The name looks a bit long to me, but that might be just personal
> preference. The code itself now looks good to me.
>
> Reviewed-by: Alexander Lobakin <aleksander.lobakin@...el.com>
>
> >  };
> >
> >  /* The structure of the shared state of the rings are a simple
>
> Next time pls make sure you added all of the reviewers to the Cc list
> when sending a new revision. I noticed you posted v4 only by monitoring
> the ML.

Oh, sorry. I always thought you were in the list. I did not notice this
situation.

I will pay attention next time. Thank you for your reply.

Thanks.


>
> Thanks,
> Olek