netdev - Re: [PATCH v2 net-next 00/14] mlx4: order-0 allocations and page recycling

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Message-ID: <c192d259-644b-0697-748f-549fdc9c11e0@gmail.com>
Date:   Thu, 9 Feb 2017 18:49:01 +0200
From:   Tariq Toukan <ttoukan.linux@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Tariq Toukan <tariqt@...lanox.com>,
        Martin KaFai Lau <kafai@...com>,
        Willem de Bruijn <willemb@...gle.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Brenden Blanco <bblanco@...mgrid.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH v2 net-next 00/14] mlx4: order-0 allocations and page
 recycling



On 09/02/2017 6:44 PM, Eric Dumazet wrote:
> On Thu, Feb 9, 2017 at 8:41 AM, Tariq Toukan <ttoukan.linux@...il.com> wrote:
>> Hi Eric,
>>
>> Thanks again for your series.
>>
>> On 09/02/2017 3:58 PM, Eric Dumazet wrote:
>>
>> As mentioned half a year ago, we better switch mlx4 driver to order-0
>> allocations and page recycling.
>>
>> This reduces vulnerability surface thanks to better skb->truesize
>> tracking and provides better performance in most cases.
>>
>> v2 provides an ethtool -S new counter (rx_alloc_pages) and
>> code factorization, plus Tariq fix.
>>
>> I see that you made significant changes to the previous series, especially
>> patch 14 (RX CQE processing).
>> Please notice that our work week has just finished here in Israel.
>> I will review the series, especially the new patches (10 to 14), on Sunday.
>>
>> We need to test this series again in our functional and performance
>> regression systems.
>> It will be running during the weekend, so we can analyze the results and
>> update you on Sunday.
>>
>> Previous performance results showed a degradation, especially in:
>> - TCP single stream at 64KB length.
> What RX ring size are you using ? I have not seen this at all.
Default, out of box.
>
>> - TCP 16 streams at 1KB length.
> TCP does not really care, it coalesces all these into TSO skbs, full size...
But the kernel stack has to split it back accordingly in the receive 
side, no?
>
>> This was probably because cache was too short, and many page allocations
>> were needed.
>> In CX4, we saw the same kind of degradation, much clearer and amplified as
>> it's 2.5 times faster (100G).
>>
>> Regards,
>> Tariq Toukan