Re: [PATCH v2] net: macb: Increase DMA TX buffer size

Path	csiph.com!aioe.org!gothmog.csi.it!bofh.it!news.nic.it!robomod
From	David Miller <davem@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] net: macb: Increase DMA TX buffer size
Date	Fri, 26 Aug 2016 02:20:01 +0200
Message-ID	<sad2h-888-9@gated-at.bofh.it> (permalink)
References	<s9LSp-6Bj-3@gated-at.bofh.it> <s9PMm-17y-23@gated-at.bofh.it>
X-Original-To	xander.huff@ni.com
MIME-Version	1.0
Content-Type	Text/Plain; charset=us-ascii
Content-Transfer-Encoding	7bit
X-Scanned-By	MIMEDefang 2.68 on 10.5.11.26
X-Greylist	Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Thu, 25 Aug 2016 23:59:07 +0000 (UTC)
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	22
Organization	linux.* mail to news gateway
X-Original-Cc	nicolas.ferre@atmel.com, netdev@vger.kernel.org, nathan.sullivan@ni.com, linux-kernel@vger.kernel.org
X-Original-Date	Thu, 25 Aug 2016 16:59:06 -0700 (PDT)
X-Original-Message-ID	<20160825.165906.1864272195425576421.davem@redhat.com>
X-Original-References	<cccfc176-df56-4add-e6c8-e040f9da31dc@atmel.com> <1472077539-18033-1-git-send-email-xander.huff@ni.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1470492

Show key headers only | View raw

From: Xander Huff <xander.huff@ni.com>
Date: Wed, 24 Aug 2016 17:25:39 -0500

> From: Nathan Sullivan <nathan.sullivan@ni.com>
> 
> In recent testing with the RT patchset, we have seen cases where the
> transmit ring can fill even with up to 200 txbds in the ring. Increase the
> size of the DMA TX ring to avoid overruns.
> 
> Signed-off-by: Xander Huff <xander.huff@ni.com>
> Signed-off-by: Nathan Sullivan <nathan.sullivan@ni.com>

This is really a short term solution.

While a larger TX ring may help RT, it's wasteful to have a ring that
large on non-RT.  Both uses are valid.

Therefore what really needs to happen is to make this driver support
changing the RX and TX ring sizes at runtime via ethtool just like
pretty much every other driver.

THanks.

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH] net: macb: Increase DMA buffer size Xander Huff <xander.huff@ni.com> - 2016-08-24 21:00 +0200
  Re: [PATCH] net: macb: Increase DMA buffer size Nicolas Ferre <nicolas.ferre@atmel.com> - 2016-08-24 21:20 +0200
    [PATCH v2] net: macb: Increase DMA TX buffer size Xander Huff <xander.huff@ni.com> - 2016-08-25 01:30 +0200
      Re: [PATCH v2] net: macb: Increase DMA TX buffer size David Miller <davem@redhat.com> - 2016-08-26 02:20 +0200

csiph-web