From: David Herrmann <dh.herrmann@gmail.com>
To: Tony Battersby <tonyb@cybernetics.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 2/6] shm: add sealing API
Date: Fri, 11 Apr 2014 02:22:13 +0200 [thread overview]
Message-ID: <CANq1E4RWf_VbzF+dPYhzHKJvnrh86me5KajmaaB1u9f9FLzftA@mail.gmail.com> (raw)
In-Reply-To: <53470E26.2030306@cybernetics.com>
Hi
On Thu, Apr 10, 2014 at 11:33 PM, Tony Battersby <tonyb@cybernetics.com> wrote:
> For O_DIRECT the kernel pins the submitted pages in memory for DMA by
> incrementing the page reference counts when the I/O is submitted,
> allowing the pages to be modified by DMA even if they are no longer
> mapped in the address space of the process. This is different from a
> regular read(), which uses the CPU to copy the data and will fail if the
> pages are not mapped.
Can you please provide an example code-path? For instance,
file_read_actor() does not pin any pages but only keeps the user-space
address and resolves it once it has data to write.
Thanks
David
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next prev parent reply other threads:[~2014-04-11 0:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-10 21:33 Tony Battersby
2014-04-11 0:22 ` David Herrmann [this message]
2014-04-11 1:27 ` Andy Lutomirski
2014-04-11 13:43 ` Tony Battersby
2014-04-11 21:31 ` David Herrmann
2014-04-11 21:36 ` Andy Lutomirski
2014-04-11 21:42 ` David Herrmann
2014-04-11 22:07 ` Andy Lutomirski
2014-04-14 0:03 ` David Herrmann
-- strict thread matches above, loose matches on Subject: below --
2014-03-19 19:06 [PATCH 0/6] File Sealing & memfd_create() David Herrmann
2014-03-19 19:06 ` [PATCH 2/6] shm: add sealing API David Herrmann
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