From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756264AbbJ1VBf (ORCPT ); Wed, 28 Oct 2015 17:01:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50101 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755731AbbJ1VBd (ORCPT ); Wed, 28 Oct 2015 17:01:33 -0400 From: Jeff Moyer To: Dan Williams Cc: Jens Axboe , Jan Kara , linux-nvdimm , Dave Hansen , david , "linux-kernel\@vger.kernel.org" , Christoph Hellwig , Andrew Morton Subject: Re: [PATCH v2 1/5] pmem, dax: clean up clear_pmem() References: <20151022171015.38343.72043.stgit@dwillia2-desk3.amr.corp.intel.com> <20151022171021.38343.65959.stgit@dwillia2-desk3.amr.corp.intel.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Wed, 28 Oct 2015 17:01:30 -0400 In-Reply-To: (Dan Williams's message of "Thu, 22 Oct 2015 15:29:33 -0700") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Williams writes: > On Thu, Oct 22, 2015 at 1:48 PM, Jeff Moyer wrote: >> Dan Williams writes: >> >>> Both, __dax_pmd_fault, and clear_pmem() were taking special steps to >>> clear memory a page at a time to take advantage of non-temporal >>> clear_page() implementations. However, x86_64 does not use >>> non-temporal instructions for clear_page(), and arch_clear_pmem() was >>> always incurring the cost of __arch_wb_cache_pmem(). >>> >>> Clean up the assumption that doing clear_pmem() a page at a time is more >>> performant. >> >> Wouldn't another solution be to actually use non-temporal stores? > > Sure. > >> Why did you choose to punt? > > Just a priority call at this point. Patches welcome of course ;-). OK. Patch is harmless. Reviewed-by: Jeff Moyer