From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755382AbbAZLP6 (ORCPT ); Mon, 26 Jan 2015 06:15:58 -0500 Received: from cpsmtpb-ews10.kpnxchange.com ([213.75.39.15]:49809 "EHLO cpsmtpb-ews10.kpnxchange.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754086AbbAZLPy (ORCPT ); Mon, 26 Jan 2015 06:15:54 -0500 Message-ID: <1422270952.9483.2.camel@x220> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to configtable as flexible requirement about IOMMU/SW-IOMMU. From: Paul Bolle To: xiaomin1 Cc: konrad.wilk@oracle.com, akpm@linux-foundation.org, linux@horizon.com, lauraa@codeaurora.org, heiko.carstens@de.ibm.com, d.kasatkin@samsung.com, takahiro.akashi@linaro.org, chris@chris-wilson.co.uk, u.kleine-koenig@pengutronix.de, linux-kernel@vger.kernel.org, Chuansheng Liu , Zhang Dongxing Date: Mon, 26 Jan 2015 12:15:52 +0100 In-Reply-To: <1422300621-4453-1-git-send-email-xiaoming.wang@intel.com> References: <1422300621-4453-1-git-send-email-xiaoming.wang@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-4.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 26 Jan 2015 11:15:52.0766 (UTC) FILETIME=[726245E0:01D03959] X-RcptDomain: vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (For some reason the "Date:" header of this message is 16 hours into the future. Ie, it claims to be for (UTC) 2015-01-26, 19.30 but actually was probably sent around (UTC) 2015-01-26, 03.30. This made this message stick at the top of the mail folder it ended up in. And that was about the only reason why I even scanned it.) On Tue, 2015-01-27 at 03:30 +0800, xiaomin1 wrote: > The maximum of SW-IOMMU is limited to 2^11*128 = 256K. > While in different platform and different requirements this seems improper. > So modify the IO_TLB_SEGSIZE to configtable is make sense. configurable? Ditto for the summary. > Example: > If 1M bytes are requied. There has an error like. required one will run into an error like: or something similar. > [ 33.293120] DMA: Out of SW-IOMMU space for 1048576 bytes at device gadget So in order to solve that and use 1M this new option needs to be set at 512? > Signed-off-by: Chuansheng Liu > Signed-off-by: Zhang Dongxing > Signed-off-by: xiaomin1 > --- > include/linux/swiotlb.h | 2 +- > lib/Kconfig | 4 ++++ > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index e7a018e..5ab10b9 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -14,7 +14,7 @@ extern int swiotlb_force; > * must be a power of 2. What is the appropriate value ? > * The complexity of {map,unmap}_single is linearly dependent on this value. > */ > -#define IO_TLB_SEGSIZE 128 > +#define IO_TLB_SEGSIZE CONFIG_DEFAULT_IO_TLB_SEGSIZE > > /* > * log of the size of each IO TLB slab. The number of slabs is command line > diff --git a/lib/Kconfig b/lib/Kconfig > index 54cf309..76f1108 100644 > --- a/lib/Kconfig > +++ b/lib/Kconfig > @@ -518,4 +518,8 @@ source "lib/fonts/Kconfig" > config ARCH_HAS_SG_CHAIN > def_bool n > > +config DEFAULT_IO_TLB_SEGSIZE > + int No "prompt", so to change this value one needs to edit the .config manually. Is that intended? > + default 128 According to include/linux/swiotlb.h this needs to be a power of 2. Shouldn't that be explained here too? Ditto the 2K unit size. And should a range of useful values be specified? (These are not rhetorical questions: I know nothing about all this. This also means I might just not be part of the intended audience for this option.) > endmenu Paul Bolle