netdev - Re: [PATCH net-next 05/12] net/mlx5e: Poll rx cq before tx cq to improve round-trip latency

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: <CAEHy93LdUDFVoxWU_++t1D5tqBSEM1TY4ZguW7QszvEyPOvagg@mail.gmail.com>
Date:	Mon, 22 Jun 2015 00:35:37 +0300
From:	achiad shochat <achiad.mellanox@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	ogerlitz@...lanox.com, netdev@...r.kernel.org, amirv@...lanox.com,
	talal@...lanox.com, saeedm@...lanox.com
Subject: Re: [PATCH net-next 05/12] net/mlx5e: Poll rx cq before tx cq to
 improve round-trip latency

Hello Dave,

In mlx5 the RX processing is broken down into two stages:
1) Hand to kernel SKBs of completed RX packets - @mlx5e_poll_rx_cq()
2) Allocate and post to HW new RX buffers - @mlx5e_post_rx_wqes()

Would handling of TX completions in between stages (1) and (2) be OK?

On 21 June 2015 at 20:21, David Miller <davem@...emloft.net> wrote:
> From: Or Gerlitz <ogerlitz@...lanox.com>
> Date: Wed, 17 Jun 2015 18:26:22 +0300
>
>> From: Achiad Shochat <achiad@...lanox.com>
>>
>> For better round trip latency, handle rx completions before
>> tx completions.
>>
>> Signed-off-by: Achiad Shochat <achiad@...lanox.com>
>> Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
>> Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
>
> I completely disagree with this change.
>
> TX completions should always be handled first because they free up resources
> and therefore increase the likelyhood that RX processing will not fail due
> to lack of resources (memory, etc.).
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
--
To unsubscribe from this list: send the line "unsubscribe netdev" in