Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755150Ab2JRMlx (ORCPT ); Thu, 18 Oct 2012 08:41:53 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:50985 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754801Ab2JRMlv (ORCPT ); Thu, 18 Oct 2012 08:41:51 -0400 Date: Thu, 18 Oct 2012 08:41:44 -0400 From: Konrad Rzeszutek Wilk To: Alexander Duyck Cc: Hillf Danton , konrad.wilk@oracle.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, rob@landley.net, akpm@linux-foundation.org, joerg.roedel@amd.com, bhelgaas@google.com, shuahkhan@gmail.com, fujita.tomonori@lab.ntt.co.jp, linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v2 1/7] swiotlb: Make io_tlb_end a physical address instead of a virtual one Message-ID: <20121018124143.GA13854@localhost.localdomain> References: <20121011203010.12444.15503.stgit@gitlad.jf.intel.com> <20121011203421.12444.32871.stgit@gitlad.jf.intel.com> <507C2F20.8000504@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <507C2F20.8000504@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2236 Lines: 53 On Mon, Oct 15, 2012 at 08:43:28AM -0700, Alexander Duyck wrote: > On 10/13/2012 05:52 AM, Hillf Danton wrote: > > Hi Alexander, > > > > On Fri, Oct 12, 2012 at 4:34 AM, Alexander Duyck > > wrote: > >> This change replaces all references to the virtual address for io_tlb_end > >> with references to the physical address io_tlb_end. The main advantage of > >> replacing the virtual address with a physical address is that we can avoid > >> having to do multiple translations from the virtual address to the physical > >> one needed for testing an existing DMA address. > >> > >> Signed-off-by: Alexander Duyck > >> --- > >> > >> lib/swiotlb.c | 24 +++++++++++++----------- > >> 1 files changed, 13 insertions(+), 11 deletions(-) > >> > >> diff --git a/lib/swiotlb.c b/lib/swiotlb.c > >> index f114bf6..19aac9f 100644 > >> --- a/lib/swiotlb.c > >> +++ b/lib/swiotlb.c > >> @@ -57,7 +57,8 @@ int swiotlb_force; > >> * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this > >> * API. > >> */ > >> -static char *io_tlb_start, *io_tlb_end; > >> +static char *io_tlb_start; > >> +phys_addr_t io_tlb_end; > > If add io_tlb_start_phy and io_tlb_end_phy, could we get same results > > with less hunks? > > > > Hillf > > What do you mean by less hunks? Are you referring to the memory space? As in less patch movements. > If so, then the patches I am submitting do not impact how much space is > used for the bounce buffer. The only real result of these patches is > that the total code path is significantly reduced since we don't have to > perform any virtual to physical translations in the hot-path. No. He is referring that you can keep io_tlb_end still here. Just do the computation of the physical address in the init path (of the end). Then you don't need to do the shifting in the 'is-this-swiotlb-buffer' and can just do a simple: if (dma_addr >= io_tlb_start && dma_addr <= io_tlb_end) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/