From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932518AbcDNSsY (ORCPT ); Thu, 14 Apr 2016 14:48:24 -0400 Received: from mail-by2on0124.outbound.protection.outlook.com ([207.46.100.124]:47648 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752332AbcDNSsV (ORCPT ); Thu, 14 Apr 2016 14:48:21 -0400 Authentication-Results: suse.cz; dkim=none (message not signed) header.d=none;suse.cz; dmarc=none action=none header.from=hpe.com; Message-ID: <570FE5E7.5000004@hpe.com> Date: Thu, 14 Apr 2016 14:48:07 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Jan Kara CC: Alexander Viro , Jan Kara , Jeff Layton , "J. Bruce Fields" , Tejun Heo , Christoph Lameter , , , Ingo Molnar , Peter Zijlstra , Andi Kleen , Dave Chinner , Boqun Feng , Scott J Norton , Douglas Hatch Subject: Re: [PATCH v7 1/4] lib/percpu-list: Per-cpu list with associated per-cpu locks References: <1460501686-37096-1-git-send-email-Waiman.Long@hpe.com> <1460501686-37096-2-git-send-email-Waiman.Long@hpe.com> <20160414141031.GE22053@quack2.suse.cz> In-Reply-To: <20160414141031.GE22053@quack2.suse.cz> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [72.71.243.58] X-ClientProxiedBy: CO2PR06CA033.namprd06.prod.outlook.com (10.141.242.33) To TU4PR84MB0320.NAMPRD84.PROD.OUTLOOK.COM (10.162.186.30) X-MS-Office365-Filtering-Correlation-Id: 79803814-fa9e-4cf4-b210-08d3649558a7 X-Microsoft-Exchange-Diagnostics: 1;TU4PR84MB0320;2:Tm2HVoGX1pmFVTEPjRgswSIEsuwvC3pTcPzTmcNQni7EkgoJDb5wPft7/wTWzOwkCRHmZQdbD3muU8vMNhtJ9lgQJ1RI50V3qBXnzv2UdCAij3EefP6O4mWfTLuMaTvippJ5mg1PoQfZzTm+ONWHEjSMiWlAE/n5KFuUN8tLxnbCN5PLOt6iDzx3fZV2qQXN;3:1lMXuqoYEgvpCT+6BfAn/OkfECzdrSlYkeyz+yfszNUy72k8mcSYg1P5DCtHHVCQB8oC/NMsR3uiL9zt0Z4GL+062FgIbi+1VX6Bk75Pvw4KtH6/NSZj0Tm/gPUEI4x5;25:z9cZFsLRyinUVQ0EklE+Lj3KxAXMz2C5Gd6Pa7yjBrKVYV6L5g7NexFCjERuIPh+mHuDUeJC4j9gNUIyLTNrfb7b9zlDyu7YFg2wTwLwuJsghumw/Kzd+Y9K/4ZkydE9zQN0TqpBdT4fh5+6dXXsqUZpCkWMQVCFkYVRDw0GDyN/yXub0yRV2bRf6OEFSujcdWuzvNx3Mm3oTB0gahyxz1MLL63gwWsP/HDOGgusSsEVQVGq31Pk6yuOjmdhsNbzxIf4Dqbz5GOeWkwCXCc7kokVuVJurss3IL9gj00nTQHrylrcQ5zKGucW7cu9huo/ywL0o7rtbTxTh/pdB+ae1g== X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:TU4PR84MB0320; 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However, if many >> threads are trying to add or delete entries into the same linked list, >> it can create a performance bottleneck. >> >> This patch introduces a new per-cpu list subystem with associated >> per-cpu locks for protecting each of the lists individually. This >> allows list entries insertion and deletion operations to happen in >> parallel instead of being serialized with a global list and lock. >> >> List entry insertion is strictly per cpu. List deletion, however, can >> happen in a cpu other than the one that did the insertion. So we still >> need lock to protect the list. Because of that, there may still be >> a small amount of contention when deletion is being done. >> >> A new header file include/linux/percpu-list.h will be added with the >> associated pcpu_list_head and pcpu_list_node structures. The following >> functions are provided to manage the per-cpu list: >> >> 1. int init_pcpu_list_head(struct pcpu_list_head **ppcpu_head) >> 2. void pcpu_list_add(struct pcpu_list_node *node, >> struct pcpu_list_head *head) >> 3. void pcpu_list_del(struct pcpu_list *node) >> >> Iteration of all the list entries within a group of per-cpu >> lists is done by calling either the pcpu_list_iterate() or >> pcpu_list_iterate_safe() functions in a while loop. They correspond >> to the list_for_each_entry() and list_for_each_entry_safe() macros >> respectively. The iteration states are keep in a pcpu_list_state >> structure that is passed to the iteration functions. >> >> Signed-off-by: Waiman Long > The patch looks good to me now. So you can add: > > Reviewed-by: Jan Kara > > Honza Thanks for the review. Cheers, Longman