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From: Saeed Mahameed <saeedm@dev.mellanox.co.il>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Saeed Mahameed <saeedm@mellanox.com>,
	"David S. Miller" <davem@davemloft.net>,
	Linux Netdev List <netdev@vger.kernel.org>,
	Or Gerlitz <ogerlitz@mellanox.com>, Tal Alon <talal@mellanox.com>,
	Tariq Toukan <tariqt@mellanox.com>,
	Eran Ben Elisha <eranbe@mellanox.com>,
	Achiad Shochat <achiad@mellanox.com>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH net-next V2 05/11] net/mlx5e: Support RX multi-packet WQE (Striding RQ)
Date: Wed, 20 Apr 2016 19:46:12 +0300	[thread overview]
Message-ID: <CALzJLG-XwPv_V51nHBxQQcsiWG20sHj0OvVacc0eVLhoQF2c8g@mail.gmail.com> (raw)
In-Reply-To: <20160419173833.GB15167@techsingularity.net>

On Tue, Apr 19, 2016 at 8:39 PM, Mel Gorman <mgorman@techsingularity.net> wrote:
> On Tue, Apr 19, 2016 at 06:25:32PM +0200, Jesper Dangaard Brouer wrote:
>> On Mon, 18 Apr 2016 07:17:13 -0700
>> Eric Dumazet <eric.dumazet@gmail.com> wrote:
>>
>
> alloc_pages_exact()
>

We want to allocate 32 order-0 physically contiguous pages and to free
each one of them individually.
the documentation states "Memory allocated by this function must be
released by free_pages_exact()"

Also it returns a pointer to the memory and we need pointers to pages.

>> > > allocates many physically contiguous pages with order0 ! so we assume
>> > > it is ok to use split_page.
>> >
>> > Note: I have no idea of split_page() performance :
>>
>> Maybe Mel knows?
>
> Irrelevant in comparison to the cost of allocating an order-5 pages if
> one is not already available.
>

we still allocate order-5 pages but now we split them to 32 order-0 pages.
the split adds extra few cpu cycles but it is lookless and
straightforward, and it does the job in terms of better memory
utilization.
now in scenarios where small packets can hold a ref on pages for too
long they would hold a ref on order-0 pages rather than order-5.

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  reply	other threads:[~2016-04-20 16:46 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-17 21:31 [PATCH net-next V2 00/11] Mellanox 100G mlx5 driver receive path optimizations Saeed Mahameed
2016-04-17 21:31 ` [PATCH net-next V2 01/11] net/mlx5: Introduce device queue counters Saeed Mahameed
2016-04-17 21:31 ` [PATCH net-next V2 02/11] net/mlx5e: Allocate set of queue counters per netdev Saeed Mahameed
2016-04-17 21:31 ` [PATCH net-next V2 03/11] net/mlx5e: Use only close NUMA node for default RSS Saeed Mahameed
2016-04-17 21:31 ` [PATCH net-next V2 04/11] net/mlx5e: Use function pointers for RX data path handling Saeed Mahameed
2016-04-17 21:31 ` [PATCH net-next V2 05/11] net/mlx5e: Support RX multi-packet WQE (Striding RQ) Saeed Mahameed
2016-04-18  0:29   ` Eric Dumazet
2016-04-18 12:48     ` Eric Dumazet
2016-04-18 13:05       ` Saeed Mahameed
2016-04-18 14:17         ` Eric Dumazet
2016-04-19 16:25           ` Jesper Dangaard Brouer
2016-04-19 17:39             ` Mel Gorman
2016-04-20 16:46               ` Saeed Mahameed [this message]
2016-04-19 18:30             ` Saeed Mahameed
2016-04-17 21:32 ` [PATCH net-next V2 06/11] net/mlx5e: Added ICO SQs Saeed Mahameed
2016-04-17 21:32 ` [PATCH net-next V2 07/11] net/mlx5e: Add fragmented memory support for RX multi packet WQE Saeed Mahameed
2016-04-17 21:32 ` [PATCH net-next V2 08/11] net/mlx5e: Use napi_alloc_skb for RX SKB allocations Saeed Mahameed
2016-04-17 21:32 ` [PATCH net-next V2 09/11] net/mlx5e: Remove redundant barrier Saeed Mahameed
2016-04-17 21:32 ` [PATCH net-next V2 10/11] net/mlx5e: Delay skb->data access Saeed Mahameed
2016-04-17 21:32 ` [PATCH net-next V2 11/11] net/mlx5e: Add ethtool counter for RX buffer allocation failures Saeed Mahameed

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