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[209.132.180.67]) by mx.google.com with ESMTP id 60-v6si5268898pld.65.2018.02.27.01.02.08; Tue, 27 Feb 2018 01:02:23 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=ibm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752402AbeB0JBP (ORCPT + 99 others); Tue, 27 Feb 2018 04:01:15 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51428 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751117AbeB0JBN (ORCPT ); Tue, 27 Feb 2018 04:01:13 -0500 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1R8we7H064774 for ; Tue, 27 Feb 2018 04:01:13 -0500 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0b-001b2d01.pphosted.com with ESMTP id 2gd34bk1ca-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Tue, 27 Feb 2018 04:01:12 -0500 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 27 Feb 2018 09:01:09 -0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w1R919kb64290938; Tue, 27 Feb 2018 09:01:09 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4617B5203F; Tue, 27 Feb 2018 07:52:56 +0000 (GMT) Received: from skywalker (unknown [9.124.35.86]) by d06av21.portsmouth.uk.ibm.com (Postfix) with SMTP id 7C18C52049; Tue, 27 Feb 2018 07:52:55 +0000 (GMT) Received: (nullmailer pid 10123 invoked by uid 1000); Tue, 27 Feb 2018 09:01:07 -0000 From: "Aneesh Kumar K.V" To: Christophe Leroy , Nicholas Piggin Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [RFC REBASED 5/5] powerpc/mm/slice: use the dynamic high slice size to limit bitmap operations In-Reply-To: <5badd882663833576c10b8aafe235fe1e443f119.1518382747.git.christophe.leroy@c-s.fr> References: <02a62db83282b5ef3e0e8281fdc46fa91beffc86.1518382747.git.christophe.leroy@c-s.fr> <5badd882663833576c10b8aafe235fe1e443f119.1518382747.git.christophe.leroy@c-s.fr> Date: Tue, 27 Feb 2018 14:31:07 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 18022709-0016-0000-0000-0000052A4711 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18022709-0017-0000-0000-000028667321 Message-Id: <87bmga7qng.fsf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-27_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802270109 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christophe Leroy writes: > The number of high slices a process might use now depends on its > address space size, and what allocation address it has requested. > > This patch uses that limit throughout call chains where possible, > rather than use the fixed SLICE_NUM_HIGH for bitmap operations. > This saves some cost for processes that don't use very large address > spaces. I haven't really looked at the final code. One of the issue we had was with the below scenario. mmap(addr, len) where addr < 128TB and addr+len > 128TB We want to make sure we build the mask such that we don't find the addr available. -aneesh