From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from YQZPR01CU011.outbound.protection.outlook.com (mail-canadaeastazon11020143.outbound.protection.outlook.com [52.101.191.143]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA0B622F767; Sat, 19 Sep 2026 17:19:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.191.143 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789838358; cv=fail; b=tibnwyKMWiqPlMi+IpeapfG9xwawUWXyM+XYQHS6bIWbMSyRdEFPpdmLddO6RED8pKEg2X8CmB5iCRUhkUrQ1sO1eYgN+9LMkfsGrnXRQaht3qK63dDPB0tX9IvY7fXqs2MpHvqH3B/nAiG71OS6wVwTdzRDoxaBUZGUzYzidkI= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789838358; c=relaxed/simple; bh=coSdeubpsu+Ov0+gqEbN7RICTviCeDhmXyPqSil7bTI=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=bmMmQU30NSGONRWSVusIe3/Bq/ZKVBK/nnXlXgdh4XUehLwjHcxnm+LVk8Rh32ZmfeHwkt9kLgzS5s79hp6IYDNOLRFF1eM6BCKiPKhn6Cfl8gB895+ILMSFSr/Znn/lMjdubvrTeKk6hjhHJZZCZAoUJleY+v4Dvno8moMNPVU= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=ae25sw5B; arc=fail smtp.client-ip=52.101.191.143 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="ae25sw5B" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=CmQm4XMbozrGjNOocZ8O79lSpWlfj1npiuAmqFiqO8VxZAUVCZp7UF/GkTP9zfOBJHXUpHW4BS+1zbWo2ScLzFRG5Ke2Lpme096U9OFNpDTV4d5qFueTQSi5pOsAIv6GYvPC5BSTmxzXdaRD6uGgFZDubXEnoA+Xz8jtzOASiRUAjpkZj4n9osYOj970vrpQwdHvM9w7YW+7XwS7VmlYG37ukKyBOIWr8gNlZxzqC8cG2ja2udv5P2CB4lwP03tf8hbZuR3DuTYDfRsvLij8xEZgQ/9PhrDTrEYxI+KQgLI4qNJzpgyqgvLsN/ZCYoEVWsPVgq/7YvBjKwtksDjjzw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=tjrvmsN0wobH3LEq7mso18M4GS8VQBp4HE9d3/CC3pg=; b=aNITGLu5dcyupqv35coCPZX+yNP+La4+HQU6fnEnePVT95nyl+Jaku5WtE8lZ/7e5JHTJOStf0UD2c1lRODwaciGWb6ATSIBNMYiE6w9q1Im19tEb+EVc4NUCHtqIYvnI/ULFUFpNKUNt9dT8zBcgyTr2eYLVOEp2QB2vTJBqJ145du+FYfaM3p0Uk8Slr45vTN/puaNGcVqSa7ELRjk/E2oYfdn09YimVQpwBtQuL8KS1A6y+M1N0kS0DckLRgwYzMzS1yTvg+MLfPHKQkgaDAzq1bWgivGFhlwIPxEgsxTIHy7+r+DtkPAI9J7MqS8s7/roDsd/mo20pWANWG2vQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=efficios.com; dmarc=pass action=none header.from=efficios.com; dkim=pass header.d=efficios.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=tjrvmsN0wobH3LEq7mso18M4GS8VQBp4HE9d3/CC3pg=; b=ae25sw5BIW1GMlZ0Uo4lyfVhpksJQU3egGpuGMgNsvs4X0thsIb4hkGaphvJd7ICOGXcGhV2rmzGDKbYsACjB0I4ZkQSV+ums1HtjL5oBbnZVkCl63QGJbCKfBPj4/4T1aWkLgMHHUD9ar1Bds73accByjWORsdGZVxeMz4tTqh1bHI6uSJiCYMULYL5C9Gg+lDEkUaMz9Hv3yT5syoKi0mqmrA2jZAYo9UDWv8DDTl1n+3DDBTw7e+VPtFamC50eJW2jvC1cznHwlW61UEeUzDn+goSewuNTqJB2XXLjk2LR3/oDXXucuCzs/Pkx0jw4FtE7enulAOqdGge/N0OiA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=efficios.com; Received: from YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:1d0::10) by YQYPR01MB11620.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:a7::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.428.14; Sat, 19 Sep 2026 17:19:13 +0000 Received: from YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM ([fe80::6b9e:a901:67c5:7ddc]) by YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM ([fe80::6b9e:a901:67c5:7ddc%6]) with mapi id 15.21.0428.014; Sat, 19 Sep 2026 17:19:12 +0000 Message-ID: Date: Sat, 19 Sep 2026 13:19:09 -0400 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/28] hazptr: Implement Hazard Pointers To: Linus Torvalds , Bradley Morgan Cc: "Paul E. McKenney" , rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Boqun Feng , Steven Rostedt , lkmm@lists.linux.dev, Zqiang , Wang Lian , Kunwu Chan , Nicholas Piggin , Michael Ellerman , Greg Kroah-Hartman , Sebastian Andrzej Siewior , Will Deacon , Peter Zijlstra , Alan Stern , John Stultz , Andrew Morton , Frederic Weisbecker , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Lai Jiangshan , Zqiang , Ingo Molnar , Waiman Long , Mark Rutland , Thomas Gleixner , Vlastimil Babka , maged.michael@gmail.com, Mateusz Guzik , Jonas Oberhauser , linux-mm@kvack.org References: <20260919000056.3132131-1-paulmck@kernel.org> <6B1FC39D-6EB0-433A-8E49-E5EFC9379AD7@mainlining.org> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: YQBPR0101CA0285.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:c01:6d::21) To YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:1d0::10) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: YT6PR01MB491026:EE_|YQYPR01MB11620:EE_ X-MS-Office365-Filtering-Correlation-Id: d3aabb90-3e5a-4480-cd33-08df16721fed X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|10070799003|1800799024|7416014|376014|366016|10067099003|56012099006|22082099003|18002099003|4143699003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(10070799003)(1800799024)(7416014)(376014)(366016)(10067099003)(56012099006)(22082099003)(18002099003)(4143699003);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 2 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?cnlxNUdDSVkySTdLRkozbHpHZjNFZy9zUHozVFFFRnVUTHN1Um1uZDZXZ0Nr?= =?utf-8?B?Yk8rOFlpZUVCVjJNMlZqQkIvVk02VDZ5WEtLTlgzU1ZCOEtiZ2hXSXVrQUJs?= =?utf-8?B?RlZOOHhlMFRsR1NJdU5DbkQwQjE4c2Z4eWZsUmlwVUZNcmpnK3k1RHBOR0I5?= =?utf-8?B?SDQxRjNUeGExdm9HNVJMTlVRNlN2Y1M0MitNdmhHM3Z4ejlRYjRuQUZSQkFU?= =?utf-8?B?QUdkMHlPSHg5amJLN2UrZTFFcy9OV29SNWNhUUdya3l0dnNxQjdSQkVIcjJS?= =?utf-8?B?Y1F5T0t3QjkxWWFwRjh0WlRpT1VxTHBRQzliWWpSVGZlMXNPc0RJbnpVWllS?= =?utf-8?B?d2ZadFJDU1BIV0VmWksrVSs4WEhrOW9mVVRrVjk3V3duZll6WkM4SXE5citl?= =?utf-8?B?QytlV3d5bDdGTXYxVG1yN0VxZXl1ckJPTjNZQ3djNUJ6SG5sNzEramZQWU5G?= =?utf-8?B?YU83Znh2NHl6ZkFHUUFFNWgxYjlvTVJEOHpUeEhwVzJldzg1Z0pXWHI2MFY5?= =?utf-8?B?V2RJWEpoVTdpbnVGS3M4V1VOUzZCR2tacS9GRU9nWXFkcExxYmN3dEhSUjdG?= =?utf-8?B?MmprbWRUQ3J4bDU3OFYrZ2ZoSDFCdG56dHUzUzJQT0U5Wm5tUWlGczJ3cmxN?= =?utf-8?B?UGZGb0daNjBmMDQzTU5kRTZDVURxMVFoRG80TW0vUlRvbEoyb1dTUXZLVW9M?= =?utf-8?B?aXNkd2M5Njg4TTF2TkRjM1Q2ZnoyNVNueU45RnFJQzlldklTRjB1YVErRDYv?= =?utf-8?B?cDQrV1pic21JRFNZYmdieU42ZmZVSmFtNkdKSEcvenVOeXRPWjluRkEvRFRI?= =?utf-8?B?QTdpR2VBRnpOaGRCSDJuZ0Rxd3Z2NTVnbmplckozcE5hcE5Xc3RuR2RhSW1T?= =?utf-8?B?YVlrZHo2dHNOd05FYUZvNVdBWlIrQjQrZkFrMWZuYjlQTGQ0WUNxZmc4REE0?= =?utf-8?B?dHAzai9FT3FBM1J6NzFNYnlkQ0xBWWs5VVgvSGlBQ0ZvdXhoalJmVzlHSW9a?= =?utf-8?B?U09VTE4za1hQNlREbmFDRGFLb3BVUFU2UHZaQXZySmpqSzh2TnRRTTBoaGtn?= =?utf-8?B?SXFvK2dVbmx4NWhiZFlWVGkyZzN3amc3eHpwaWd4WHMwU1BlMndxc2s5Q0Ri?= =?utf-8?B?dzRucXpzQldSUHFYTTdsaXBldEhTNmJVeE5Cd2VjN1Roak15N2hIZnY2aWJN?= =?utf-8?B?dllGcGZCK3BTRmJIei9KVDlrYkpnZ05lSExzNHIrd0ZIbHV1SVFidzFWcFFI?= =?utf-8?B?VXlPY1pjdGRmcHY3YlRaNnVWb0xycTV5MWNKU3JuVm9CaVA3YjBtaHoxNGlS?= =?utf-8?B?YVVHclJnTHVjc0hrY2pwRXlLYmVBbzg5ZFVBQ3JEWnpyYkxudjdqaGpWYVdw?= =?utf-8?B?L3lMTXc3ZEk3THJVaXM4TWdiZE1leDlGY0VEL29iRVFjMExkWVJwSVo5RTlZ?= =?utf-8?B?S3dXaVB3QWR0UllnMU85UGZBRDY2cm15M0VVc0kvQ0pCV2hlNTYyOCsyWGhy?= =?utf-8?B?WkdEZVJDOHRRYnp1dlVJRGVxV2dGRDNPNVdrOEw3YUNHb2hVS1ZXaklNdnhx?= =?utf-8?B?TmM1WTNQQlNRZE4wTGVxdnBnT3ZRbURpa2pDZFd2RzRWYnFFVFhRczJUWWVw?= =?utf-8?B?cXM3MjdJN2d1QzJtZTVYR1ZDUE1NRFBlTWVGNmtsa1FJa2RsSlRIOW9jTm9r?= =?utf-8?B?WEZFYkRXM0R4bVhZVzJKbnhvaFlPSE1DZkthc09STC9HcG53QmdoVWsyUjk5?= =?utf-8?B?MnNja011bUl5OGd1NDdDc1VTSWtzdDB2Q2NnbUFkR1RNM3RQajlid0RQWFBW?= =?utf-8?B?a3hRbzhHN0pwUUwydVUrbndXb2EyVm4wNHFlR2t3Y1FWYjF1RE5GeHRIN0VU?= =?utf-8?B?V0NuQmpRNTJ5ZUxYdkJRWWFFTmRmYzZHS1hWUTRwVkxqV1Z4M2NKN21lMlpV?= =?utf-8?B?RXl4U2lmM0xNYjFQMHFkT0NUaFVSemxtVVVmWW1ncWFWSFdlVDhsKzJNOWpQ?= =?utf-8?B?V3dBWHhiTngyNXZOTFh1SDZiUFF0dTdHUWh5d0NaY0lRTkJqQlA2NElmU3o3?= =?utf-8?B?Vm1nbVBPUjFBRUVOakdTTmZ2c1hwbjVVb1hhb3U0QzFHVjhvYkM0Qlp1VEx6?= =?utf-8?B?OHpyMldqd0EveERsdlVBK1UwZ0NuUEp6b1lmWXNPTjd4MGlpZFpVQVUwcGNw?= =?utf-8?B?dDRPNWdjOG0xZXdMODYyYTZodlZxTDRaZ3M0aUwrTVk2dE5EditrRmkyNEhn?= =?utf-8?B?MEZIRDRrK3llbVd2cTdnWDJPUStaRHhJdkkwZEk0VWpvMlBpQVJGSmpjRVJ6?= =?utf-8?B?U0xCYUxLZnJWT1BqRWF0VGlmMXNJK1RZMUZ5SzZWQTAxVDc0UG9oRzVQcllp?= =?utf-8?Q?AKORDrqgFaGV1/ZnXHrY9hLTYoVTxLdgu76JCm+tlqGkR?= X-MS-Exchange-AntiSpam-MessageData-1: gzxVEZj0f4WNZlfQxS2fj8l7nlSIQti7f/w= X-OriginatorOrg: efficios.com X-MS-Exchange-CrossTenant-Network-Message-Id: d3aabb90-3e5a-4480-cd33-08df16721fed X-MS-Exchange-CrossTenant-AuthSource: YT6PR01MB491026.CANPRD01.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Sep 2026 17:19:12.8590 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4f278736-4ab6-415c-957e-1f55336bd31e X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: SjR8/+Xfrm5zgGR2WswMAiLOGALHmBduyyBU7FAEdOg9LLe5zK2GWPI3LQozrju2YiQFzrPHduFRa8YBjER+ZWjIoeAGIAsgLQ7qOmN8J1k= X-MS-Exchange-Transport-CrossTenantHeadersStamped: YQYPR01MB11620 On 2026-09-19 13:00, Linus Torvalds wrote: [...] > Now, obviously, the thing that would impress me is something like the > dcache. If *that* can be converted, and it shows real improvements on > some real benchmark, then I'm sold. [ Side-discussion, not related to hazard pointers. ] Talking about dcache improvements: I've been working on scalability of rename, directory move, and directory listing, basically killing dcache global locks, seqlocks and rwlocks which significantly limit dcache update and read-side scalability. Those improvements are based on RCU, not hazard pointers, and on a new "RCU pseudo-transaction" concept I've invented earlier this year. I'm preparing a paper and I plan to present it at LPC in Prague. My benchmark results are on a userspace port of the Linux kernel dentry cache at this point, so it's not ready for anything close to upstream at this stage. Cheers, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com