From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 213FFC49ED7 for ; Tue, 10 Sep 2019 22:12:09 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E7B05216F4 for ; Tue, 10 Sep 2019 22:12:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tdmx/Vtl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E7B05216F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=gmkvukvGj6xKKfnhaaDvst8gB3u+rtI4D1uyjW+6LP4=; b=tdmx/VtlKx+IDQ ckFfix9okkjm4xw9c8ypB9qFDBVxTH5TaulMn7Eirt06DsqBKBzEL3NkqUbks26pEVvEQAlf3FJwt fcyZ3PgYDRgu2L45xwIUh6cnsrl91b0N8626lyGAncBEWKRWTh/eL+9fgOGy47g8haRYbE8R5wZJR A+M1wUADjcfQw7LPotnGhwQDk50IBom17rCTeAUVVkBlOGDSCp3EiDq7qbxRzWqxYjlg1h4ClEtCm Y6j6rGt50LMy5tGuXRl3Z1Om/ZhdsKQpvu6bODAfpXUMEtJRBKOMTiCAL1s35c5BkKC7qVssA+ktB 6iJk2qfrSj5wxoJJz39w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i7oMd-00013c-UM; Tue, 10 Sep 2019 22:11:56 +0000 Received: from mga01.intel.com ([192.55.52.88]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i7oMa-00013G-AS for linux-arm-kernel@lists.infradead.org; Tue, 10 Sep 2019 22:11:53 +0000 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Sep 2019 15:11:51 -0700 X-IronPort-AV: E=Sophos;i="5.64,490,1559545200"; d="scan'208";a="268551180" Received: from ahduyck-desk1.jf.intel.com ([10.7.198.76]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Sep 2019 15:11:50 -0700 Message-ID: <3de2409415b20440d5c8f3016ed78fde3d106dc8.camel@linux.intel.com> Subject: Re: [PATCH v9 1/8] mm: Add per-cpu logic to page shuffling From: Alexander Duyck To: David Hildenbrand , Alexander Duyck , virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org, mst@redhat.com, catalin.marinas@arm.com, dave.hansen@intel.com, linux-kernel@vger.kernel.org, willy@infradead.org, mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, will@kernel.org, linux-arm-kernel@lists.infradead.org, osalvador@suse.de Date: Tue, 10 Sep 2019 15:11:50 -0700 In-Reply-To: <0df2e5d0-af92-04b4-aa7d-891387874039@redhat.com> References: <20190907172225.10910.34302.stgit@localhost.localdomain> <20190907172512.10910.74435.stgit@localhost.localdomain> <0df2e5d0-af92-04b4-aa7d-891387874039@redhat.com> User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190910_151152_437712_33E5CDD6 X-CRM114-Status: GOOD ( 11.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com, konrad.wilk@oracle.com, ying.huang@intel.com, lcapitulino@redhat.com, wei.w.wang@intel.com, aarcange@redhat.com, nitesh@redhat.com, pbonzini@redhat.com, dan.j.williams@intel.com, fengguang.wu@intel.com, kirill.shutemov@linux.intel.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 2019-09-09 at 10:14 +0200, David Hildenbrand wrote: > On 07.09.19 19:25, Alexander Duyck wrote: > > From: Alexander Duyck > > > > Change the logic used to generate randomness in the suffle path so that we > > can avoid cache line bouncing. The previous logic was sharing the offset > > and entropy word between all CPUs. As such this can result in cache line > > bouncing and will ultimately hurt performance when enabled. > > So, usually we perform such changes if there is real evidence. Do you > have any such performance numbers to back your claims? I don't have any numbers. From what I can tell the impact is small enough that this doesn't really have much impact. With that being the case I can probably just drop this patch. I will instead just use "rand & 1" in the 2nd patch to generate the return value which was what was previously done in add_to_free_area_random. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel