From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id DAA51900138 for ; Thu, 18 Aug 2011 04:28:28 -0400 (EDT) Subject: RE: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings From: Tixy In-Reply-To: <009101cc5cde$6dfaa660$49eff320$%szyprowski@samsung.com> References: <1313146711-1767-1-git-send-email-m.szyprowski@samsung.com> <201108161626.26130.arnd@arndb.de> <006b01cc5cb3$dac09fa0$9041dee0$%szyprowski@samsung.com> <201108171428.44555.arnd@arndb.de> <009101cc5cde$6dfaa660$49eff320$%szyprowski@samsung.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 18 Aug 2011 09:27:53 +0100 Message-ID: <1313656073.2254.23.camel@computer2> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski Cc: 'Arnd Bergmann' , 'Ankita Garg' , 'Daniel Walker' , 'Russell King - ARM Linux' , 'Jesse Barker' , 'Mel Gorman' , 'Chunsang Jeong' , 'Jonathan Corbet' , linux-kernel@vger.kernel.org, 'Michal Nazarewicz' , linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, 'Kyungmin Park' , 'KAMEZAWA Hiroyuki' , 'Shariq Hasnain' , 'Andrew Morton' , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org On Wed, 2011-08-17 at 15:06 +0200, Marek Szyprowski wrote: [...] > > > Maybe for the first version a static pool with reasonably small size > > > (like 128KiB) will be more than enough? This size can be even board > > > depended or changed with kernel command line for systems that really > > > needs more memory. > > > > For a first version that sounds good enough. Maybe we could use a fraction > > of the CONSISTENT_DMA_SIZE as an estimate? > > Ok, good. For the initial values I will probably use 1/8 of > CONSISTENT_DMA_SIZE for coherent allocations. Writecombine atomic allocations > are extremely rare and rather ARM specific. 1/32 of CONSISTENT_DMA_SIZE should > be more than enough for them. For people who aren't aware, we have a patch to remove the define CONSISTENT_DMA_SIZE and replace it with a runtime call to an initialisation function [1]. I don't believe this fundamentally changes anything being discussed though. -- Tixy [1] http://www.spinics.net/lists/arm-kernel/msg135589.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org