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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Mike Frysinger <vapier.adi@gmail.com>
Cc: "Christoph Lameter" <cl@linux.com>,
	"Pekka Enberg" <penberg@cs.helsinki.fi>,
	"Matt Mackall" <mpm@selenic.com>,
	"Dmitry Torokhov" <dmitry.torokhov@gmail.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Oskar Schirmer" <os@emlix.com>,
	"Michael Hennerich" <Michael.Hennerich@analog.com>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Daniel Glöckner" <dg@emlix.com>,
	"Oliver Schneidewind" <osw@emlix.com>,
	"Johannes Weiner" <jw@emlix.com>, "Nick Piggin" <npiggin@suse.de>,
	"David Rientjes" <rientjes@google.com>,
	"David Brownell" <dbrownell@users.sourceforge.net>,
	"Grant Likely" <grant.likely@secretlab.ca>
Subject: Re: [PATCH v3] ad7877: keep dma rx buffers in seperate cache lines
Date: Tue, 11 May 2010 23:37:42 +0100	[thread overview]
Message-ID: <20100511233742.61cf0a6b@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <AANLkTilEfZLWYxPmCQ1KHIvUGIF_8Qchali66wHNf2gB@mail.gmail.com>

> SPI transfer into a DMA safe buffer.  what is the exact API to
> dynamically allocate memory for the structure with this buffer
> embedded in it such that the start of the structure is cached aligned
> ?  creating a dedicated kmem cache may work, but it isnt a scalable
> solution if every SPI driver needs to create its own cache.

If you are embedding structures then one solution is to cheat a bit and
make the structure, compiler and existing kernel compile abuse do the
work. Something like

struct {
	void *except_where_prohibited;
	long boat;
	unsigned photograph;

	u8 pad[0] __cacheline_aligned;
}..

ought to do the trick providing you align the start of the object - which
should happen naturally with kmalloc or dma_* apis



  parent reply	other threads:[~2010-05-11 22:33 UTC|newest]

Thread overview: 124+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-06 10:37 [PATCH] ad7877: fix spi word size to 16 bit Oskar Schirmer
2010-05-06 10:37 ` Oskar Schirmer
2010-05-06 10:37 ` [PATCH] ad7877: keep dma rx buffers in seperate cache lines Oskar Schirmer
2010-05-06 18:46   ` Mike Frysinger
2010-05-06 18:46     ` Mike Frysinger
2010-05-07 10:15     ` Oskar Schirmer
2010-05-07 10:15       ` Oskar Schirmer
2010-05-07 18:28       ` Mike Frysinger
2010-05-07 18:28         ` Mike Frysinger
2010-05-08 22:32         ` Johannes Weiner
2010-05-08 22:32           ` Johannes Weiner
2010-05-09  4:45           ` Mike Frysinger
2010-05-09  4:45             ` Mike Frysinger
2010-05-09  8:50             ` Oskar Schirmer
2010-05-09  8:50               ` Oskar Schirmer
2010-05-07 12:07     ` Johannes Weiner
2010-05-10 10:34   ` [PATCH v2] " Oskar Schirmer
2010-05-10 10:34     ` Oskar Schirmer
2010-05-10 10:42     ` [PATCH v3] " Oskar Schirmer
2010-05-10 10:42       ` Oskar Schirmer
2010-05-10 16:39       ` Mike Frysinger
2010-05-10 20:54         ` Dmitry Torokhov
2010-05-10 21:22       ` Andrew Morton
2010-05-10 21:27         ` Mike Frysinger
2010-05-11  6:05         ` Dmitry Torokhov
2010-05-11  6:05           ` Dmitry Torokhov
2010-05-11  6:11           ` Mike Frysinger
2010-05-11  6:11             ` Mike Frysinger
2010-05-11  3:20             ` Andrew Morton
2010-05-11  6:21             ` Dmitry Torokhov
2010-05-11  6:23               ` Mike Frysinger
2010-05-11  6:23                 ` Mike Frysinger
2010-05-11  6:33                 ` Dmitry Torokhov
2010-05-11  6:33                   ` Dmitry Torokhov
2010-05-11  6:37                   ` Mike Frysinger
2010-05-11  6:42                   ` Pekka Enberg
2010-05-11 13:57                     ` Christoph Lameter
2010-05-11 16:52                     ` Dmitry Torokhov
2010-05-11 17:31                       ` Mike Frysinger
2010-05-11 18:59                       ` Pekka Enberg
2010-05-11 20:03                     ` Mike Frysinger
2010-05-11 20:07                       ` Matt Mackall
2010-05-11 20:10                         ` Mike Frysinger
2010-05-11 20:10                           ` Mike Frysinger
2010-05-11 20:21                           ` Christoph Lameter
2010-05-11 20:34                             ` Mike Frysinger
2010-05-11 20:38                               ` Pekka Enberg
2010-05-11 20:43                                 ` Mike Frysinger
2010-05-11 20:43                                   ` Mike Frysinger
2010-05-11 20:47                                   ` Pekka Enberg
2010-05-13  6:21                                     ` Paul Mundt
2010-05-11 20:46                               ` Christoph Lameter
2010-05-11 20:54                                 ` Mike Frysinger
2010-05-11 20:54                                   ` Mike Frysinger
2010-05-11 21:01                                   ` Pekka Enberg
2010-05-11 21:11                                     ` Mike Frysinger
2010-05-11 21:11                                       ` Mike Frysinger
2010-05-12  1:58                                     ` FUJITA Tomonori
     [not found]                                   ` <20100511214836.GH1726@emlix.com>
2010-05-11 21:53                                     ` Dmitry Torokhov
2010-05-11 22:39                                       ` Mike Frysinger
2010-05-11 22:39                                         ` Mike Frysinger
2010-05-12  2:07                                         ` [LKML] " Marc Gauthier
2010-05-12  3:03                                           ` Nick Piggin
2010-05-12  3:23                                             ` FUJITA Tomonori
2010-05-12  4:35                                               ` Mike Frysinger
2010-05-12  4:35                                                 ` Mike Frysinger
2010-05-12  5:28                                                 ` FUJITA Tomonori
2010-05-12  5:28                                                   ` FUJITA Tomonori
2010-05-12 14:37                                                   ` Mike Frysinger
2010-05-12 14:37                                                     ` Mike Frysinger
2010-05-12 18:11                                                     ` Dmitry Torokhov
2010-05-12 18:28                                                       ` Mike Frysinger
2010-05-12 18:28                                                         ` Mike Frysinger
2010-05-12 10:36                                                 ` Johannes Weiner
2010-05-12 12:35                                                 ` Marc Gauthier
2010-05-12 14:36                                                   ` Mike Frysinger
2010-05-12 14:36                                                     ` Mike Frysinger
2010-05-19 12:48                                             ` David Woodhouse
2010-05-19 13:07                                               ` Nick Piggin
2010-05-19 13:17                                                 ` David Woodhouse
2010-05-19 13:36                                                   ` Nick Piggin
2010-05-19 13:44                                                     ` Johannes Weiner
2010-05-19 13:52                                                       ` Nick Piggin
2010-05-19 14:38                                                         ` FUJITA Tomonori
2010-05-19 14:58                                                           ` David Woodhouse
2010-05-20  4:42                                                             ` FUJITA Tomonori
2010-05-19 16:37                                                           ` Dmitry Torokhov
2010-05-19 15:00                                                         ` Johannes Weiner
2010-05-17  6:12                                         ` Michal Simek
2010-05-19 13:00                                   ` David Woodhouse
2010-05-11 22:37                               ` Alan Cox [this message]
2010-05-11 20:22                           ` Pekka Enberg
2010-05-11 14:12           ` Oskar Schirmer
2010-05-11 14:12             ` Oskar Schirmer
2010-05-06 11:18 ` [PATCH] ad7877: fix spi word size to 16 bit Hennerich, Michael
2010-05-06 11:18   ` Hennerich, Michael
2010-05-06 18:26 ` Mike Frysinger
2010-05-06 18:26   ` Mike Frysinger
2010-05-07  9:41   ` Daniel Glöckner
2010-05-07  9:41     ` Daniel Glöckner
2010-05-07 18:23     ` Mike Frysinger
2010-05-07 18:23       ` Mike Frysinger
2010-05-13  7:53       ` Dmitry Torokhov
2010-05-13  7:53         ` Dmitry Torokhov
2010-05-15 18:15         ` Oskar Schirmer
2010-05-15 18:15           ` Oskar Schirmer
2010-05-16 19:25           ` Mike Frysinger
2010-05-16 19:25             ` Mike Frysinger
2010-05-17  7:29             ` Oskar Schirmer
2010-05-17  7:29               ` Oskar Schirmer
2010-05-17  8:14               ` Hennerich, Michael
2010-05-17  8:14                 ` Hennerich, Michael
2010-05-17  8:41                 ` Oskar Schirmer
2010-05-17  8:41                   ` Oskar Schirmer
2010-05-17 23:49               ` Mike Frysinger
2010-05-17 23:49                 ` Mike Frysinger
2010-05-18  0:18                 ` H Hartley Sweeten
2010-05-18  0:18                   ` H Hartley Sweeten
2010-05-18  8:32                   ` Oskar Schirmer
2010-05-18  8:32                     ` Oskar Schirmer
2010-05-18  9:37                 ` Daniel Glöckner
2010-05-18  9:37                   ` Daniel Glöckner
2010-05-18  8:34 ` [PATCH v2] " Oskar Schirmer
2010-05-18  8:34   ` Oskar Schirmer

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