netdev - Re: [PATCH net-next V2 05/11] net/mlx5e: Support RX multi-packet WQE (Striding RQ)

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Message-ID: <CALzJLG_W9SkgMBQp86P0WDknw4Kc=DCBrvpPemAUbRX=r4r8Yg@mail.gmail.com>
Date:	Mon, 18 Apr 2016 16:05:42 +0300
From:	Saeed Mahameed <saeedm@....mellanox.co.il>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Saeed Mahameed <saeedm@...lanox.com>,
	"David S. Miller" <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Tal Alon <talal@...lanox.com>,
	Tariq Toukan <tariqt@...lanox.com>,
	Eran Ben Elisha <eranbe@...lanox.com>,
	Achiad Shochat <achiad@...lanox.com>
Subject: Re: [PATCH net-next V2 05/11] net/mlx5e: Support RX multi-packet WQE
 (Striding RQ)

On Mon, Apr 18, 2016 at 3:48 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Sun, 2016-04-17 at 17:29 -0700, Eric Dumazet wrote:
>
>>
>> If really you need to allocate physically contiguous memory, have you
>> considered converting the order-5 pages into 32 order-0 ones ?
>
> Search for split_page() call sites for examples.
>
>

Thanks Eric, we are already evaluating split_page as we speak.

We did look but could not find any specific alloc_pages API that
allocates many physically contiguous pages with order0 ! so we assume
it is ok to use split_page.

BTW our MPWQE solution doesn't totally rely on huge physically
contiguous memory, as you see in the next two patches we introduce a
fragmented MPWQE approach as a fallback, but we do understand your
concern for the normal flow.