LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Nelson, Shannon" <shannon.nelson@intel.com>
To: "Haavard Skinnemoen" <hskinnemoen@atmel.com>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	<linux-kernel@vger.kernel.org>
Subject: RE: [RFC v3 4/7] dmaengine: Add slave DMA interface
Date: Tue, 19 Feb 2008 10:46:54 -0800	[thread overview]
Message-ID: <BAE9DCEF64577A439B3A37F36F9B691C040CB607@orsmsx418.amr.corp.intel.com> (raw)
In-Reply-To: <20080218142949.2c5b2810@dhcp-252-066.norway.atmel.com>

>From: Haavard Skinnemoen [mailto:hskinnemoen@atmel.com] 
>Sent: Monday, February 18, 2008 5:30 AM
>To: Nelson, Shannon
>Cc: Haavard Skinnemoen; Williams, Dan J; 
>linux-kernel@vger.kernel.org; David Brownell; 
>kernel@avr32linux.org; Francis Moreau; Paul Mundt; Vladimir A. 
>Barinov; Pierre Ossman
>Subject: Re: [RFC v3 4/7] dmaengine: Add slave DMA interface
>
>On Fri, 15 Feb 2008 09:12:35 -0800
>"Nelson, Shannon" <shannon.nelson@intel.com> wrote:
>
>> I'll jump in here briefly - I'm okay with the direction this 
>is going,
>> but I want to be protective of ioatdma performance.  As used 
>in struct
>> ioat_desc_sw, the cookie and ack elements end up very close 
>to the end
>> of a cache line and I'd like them to not get pushed out across the
>> boundry.  I don't think this proposal changes the layout, I'm just
>> bringing up my concern.
>
>Sure, performance is very important, and it's good to see that you're
>critical about the changes I'm proposing. That said, the memory layout
>doesn't change at all with this patch -- the fields that didn't go into
>the generic dma descriptor were at the end of the struct to begin with.
>
>I can add a comment saying that cookie and ack must always come first.
>Any other fields that we need to be careful about?
>
>Haavard
>

Those are the only two that I'm worried about at the moment.  I'm just
hoping that a quirk in some compiler's struct packing doesn't push them
over that edge.

Thanks,
sln

  reply	other threads:[~2008-02-19 18:55 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-12 16:43 [RFC v3 1/7] dmaengine: Couple DMA channels to their physical DMA device Haavard Skinnemoen
2008-02-12 16:43 ` [RFC v3 2/7] dmaengine: Add dma_client parameter to device_alloc_chan_resources Haavard Skinnemoen
2008-02-12 16:43   ` [RFC v3 3/7] dmaengine: Add dma_chan_is_in_use() function Haavard Skinnemoen
2008-02-12 16:43     ` [RFC v3 4/7] dmaengine: Add slave DMA interface Haavard Skinnemoen
2008-02-12 16:43       ` [RFC v3 5/7] dmaengine: Make DMA Engine menu visible for AVR32 users Haavard Skinnemoen
2008-02-12 16:43         ` [RFC v3 6/7] dmaengine: Driver for the Synopsys DesignWare DMA controller Haavard Skinnemoen
2008-02-12 16:43           ` [RFC v3 7/7] Atmel MCI: Driver for Atmel on-chip MMC controllers Haavard Skinnemoen
2008-02-12 20:43         ` [RFC v3 5/7] dmaengine: Make DMA Engine menu visible for AVR32 users Olof Johansson
2008-02-12 22:13           ` Haavard Skinnemoen
2008-02-12 22:27             ` Dan Williams
2008-02-13  8:44               ` Haavard Skinnemoen
2008-02-13  7:21       ` [RFC v3 4/7] dmaengine: Add slave DMA interface Dan Williams
2008-02-13  8:03         ` Haavard Skinnemoen
2008-02-13 19:07       ` Dan Williams
2008-02-13 19:24         ` Haavard Skinnemoen
2008-02-15  9:53           ` Haavard Skinnemoen
2008-02-15 17:12             ` Nelson, Shannon
2008-02-18 13:29               ` Haavard Skinnemoen
2008-02-19 18:46                 ` Nelson, Shannon [this message]
2008-02-16 20:06             ` Dan Williams
2008-02-18 13:22               ` Haavard Skinnemoen
2008-02-18 22:42                 ` Dan Williams

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=BAE9DCEF64577A439B3A37F36F9B691C040CB607@orsmsx418.amr.corp.intel.com \
    --to=shannon.nelson@intel.com \
    --cc=dan.j.williams@intel.com \
    --cc=hskinnemoen@atmel.com \
    --cc=linux-kernel@vger.kernel.org \
    --subject='RE: [RFC v3 4/7] dmaengine: Add slave DMA interface' \
    /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).