netdev - Re: [PATCH v3 net-next 08/14] mlx4: use order-0 pages for RX

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKgT0Uex--jLtBtJ+wp8wmkZuUfTu7ktYTvBF9623Ztm_NrGxw@mail.gmail.com>
Date:   Mon, 13 Feb 2017 15:47:23 -0800
From:   Alexander Duyck <alexander.duyck@...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>,
        Saeed Mahameed <saeedm@...lanox.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 v3 net-next 08/14] mlx4: use order-0 pages for RX

On Mon, Feb 13, 2017 at 3:29 PM, Eric Dumazet <edumazet@...gle.com> wrote:
> On Mon, Feb 13, 2017 at 3:26 PM, Alexander Duyck
> <alexander.duyck@...il.com> wrote:
>
>>
>> Odds are for a single TCP flow you won't notice.  This tends to be
>> more of a small packets type performance issue.  If you hammer on he
>> Rx using pktgen you would be more likely to see it.
>>
>> Anyway patch looks fine from a functional perspective so I am okay
>> with it.  The page count bulking is something that can be addressed
>> later.
>
> Well, if we hammer enough, pages are not recycled because we cycle
> through RX ring buffer too fast.
>
> This might be different for PowerPC though, because of its huge PAGE_SIZE.

Actually it depends on the use case.  In the case of pktgen packets
they are usually dropped pretty early in the receive path.  Think
something more along the lines of a TCP syn flood versus something
that would be loading up a socket.

- Alex