From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f54.google.com (mail-wg0-f54.google.com [74.125.82.54]) by kanga.kvack.org (Postfix) with ESMTP id C38C36B0032 for ; Thu, 14 May 2015 17:52:20 -0400 (EDT) Received: by wgnd10 with SMTP id d10so88046800wgn.2 for ; Thu, 14 May 2015 14:52:20 -0700 (PDT) Received: from mail-wg0-f48.google.com (mail-wg0-f48.google.com. [74.125.82.48]) by mx.google.com with ESMTPS id u1si245955wiy.106.2015.05.14.14.52.18 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 14 May 2015 14:52:19 -0700 (PDT) Received: by wgin8 with SMTP id n8so90542911wgi.0 for ; Thu, 14 May 2015 14:52:18 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1431551151-19124-11-git-send-email-toshi.kani@hp.com> References: <1431551151-19124-1-git-send-email-toshi.kani@hp.com> <1431551151-19124-11-git-send-email-toshi.kani@hp.com> Date: Thu, 14 May 2015 14:52:18 -0700 Message-ID: Subject: Re: [PATCH v9 10/10] drivers/block/pmem: Map NVDIMM with ioremap_wt() From: Dan Williams Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Andrew Morton , Arnd Bergmann , jgross@suse.com, Konrad Rzeszutek Wilk , "linux-nvdimm@lists.01.org" , mcgrof@suse.com, X86 ML , "linux-kernel@vger.kernel.org" , stefan.bader@canonical.com, Andy Lutomirski , linux-mm@kvack.org, hmh@hmh.eng.br, Christoph Hellwig , Matthew Wilcox On Wed, May 13, 2015 at 2:05 PM, Toshi Kani wrote: > The pmem driver maps NVDIMM with ioremap_nocache() as we cannot > write back the contents of the CPU caches in case of a crash. > > This patch changes to use ioremap_wt(), which provides uncached > writes but cached reads, for improving read performance. I'm thinking that for the libnd integration we don't want the pmem driver hard coding the cache-policy decision. This is something that should be specified to nd_pmem_region_create(). Especially considering that platform firmware tables (NFIT) may specify the cache policy for the range. As Matthew Wilcox mentioned offline we also must match the DAX-to-mmap cache policy with the policy for the driver mapping for architectures that are not capable of multiple mappings of the same physical address with different policies. -- 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/ . Don't email: email@kvack.org