LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Loic Poulain <loic.poulain@linaro.org>
To: richard.laing@alliedtelesis.co.nz
Cc: David Miller <davem@davemloft.net>,
	Network Development <netdev@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bus: mhi: pci-generic: configurable network interface MRU
Date: Mon, 19 Jul 2021 12:11:26 +0200	[thread overview]
Message-ID: <CAMZdPi-1E5pieVwt_XFF-+PML-cX05nM=PdD0pApD_ym5k_uMQ@mail.gmail.com> (raw)
In-Reply-To: <20210714211805.22350-1-richard.laing@alliedtelesis.co.nz>

Hi Richard,

On Wed, 14 Jul 2021 at 23:18, <richard.laing@alliedtelesis.co.nz> wrote:
>
> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
>
> The MRU value used by the MHI MBIM network interface affects
> the throughput performance of the interface. Different modem
> models use different default MRU sizes based on their bandwidth
> capabilities. Large values generally result in higher throughput
> for larger packet sizes.


For my interest do you have some numbers here highlighting improvement?

> In addition if the MRU used by the MHI device is larger than that
> specified in the MHI net device the data is fragmented and needs
> to be re-assembled which generates a (single) warning message about
> the fragmented packets. Setting the MRU on both ends avoids the
> extra processing to re-assemble the packets.


Re-assembly is quite free since it's about chaining buffers (no copy
or re-alloc).

>
>
> This patch allows the documented MRU for a modem to be automatically
> set as the MHI net device MRU avoiding fragmentation and improving
> throughput performance.


I would be interested in some numbers (throughput, CPU usage...) since
I've not been able to test that at very high throughput for MBIM. The
default MRU has been set so that MHI packets fit into 4K pages, for
faster allocation. As you said, that causes more MHI transfers but
there is Interrupt Coalescing at hardware level, which mitigates
overhead.

Regards,
Loic

  parent reply	other threads:[~2021-07-19 10:01 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 21:18 richard.laing
2021-07-15 17:20 ` patchwork-bot+netdevbpf
2021-07-19 10:11 ` Loic Poulain [this message]
2021-07-19 21:44   ` Richard Laing
2021-07-27  9:21     ` Loic Poulain
2021-07-27 20:49       ` Richard Laing

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAMZdPi-1E5pieVwt_XFF-+PML-cX05nM=PdD0pApD_ym5k_uMQ@mail.gmail.com' \
    --to=loic.poulain@linaro.org \
    --cc=davem@davemloft.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=richard.laing@alliedtelesis.co.nz \
    --subject='Re: [PATCH] bus: mhi: pci-generic: configurable network interface MRU' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).