From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2057.outbound.protection.outlook.com [40.107.243.57]) (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 1CDB517B500; Thu, 6 Mar 2025 15:33:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.243.57 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741275211; cv=fail; b=U8eCwdYzwUjD1XZDtpwfQsQknQDluPandFRkXCO21TqGetKAiT7JNP03q0CqG4QWfsEE+2j94uunZUWJ9zLFHw5gC7ihcqUnLV9oCYc8xXEqbpVPANguLz6zpnpSN0JAvQMpdVjtJtkm1alZX59iX4PwGFgKy9WyvRuCBs4omKU= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741275211; c=relaxed/simple; bh=p/j9mwB6ozP5NNuJJ7luLfaDtqCbHchIvogxFZwgqbA=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=h/tauk2+WWnLLCEF38qIPLLeUsEtidn/pZqoKAVtNRLNrznMyP8/uuULpJZ5AlGYdaj9BMBu1z5gj+uK8KPlYgETV7dLTGIlqAQhgXPu698WREKe0TPSd2R0PtPHfdZ7xvJfdY//MD7WpC50s5vHGU8f1BNpz3Gqgszk4mKmaig= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=kx7k6MT5; arc=fail smtp.client-ip=40.107.243.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="kx7k6MT5" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=kKhjiOskQCs+pUwAr+U0x876Tx8+eNMGu4QyaZ9VDgtSxoNSe0OKJEwCLMXDmaSUt7XLa4yVjNoVmk8CQCijAOT/eLWNncNwmk8DyLUSK0bT6fH2oRlYWj52/GjgLHGFV+FmCjCERpkDIdoU8ZVyibNJauzbQILf2XnKML+Mmk56w7KOg1M9v4iHI/5P5DEpD2e6Jovr8m5ui+7vB+GVbgLRg6zaL5/AR+U633H7DW/aMtCEs0vFx/BOOCrXnkyaQz99jl4D/Mh2hX6bTzu+3Q0mHVrTlaDp+XuaT1PpHx4EGW/DBIGOxtlDu7US2fjEEzKBRPeMr9hJLx14BduP4A== 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=XTc+83HyaYqpRAllhCZ1EK1SMHyS3pZOvOBym1l5jYE=; b=Cjtj82NHQBRqHgS+GPIw/8L1DGRMOo7fnQHFs6YcJB5OWQ7D81nvlmHacI8igKJ/1P6rDT3inSSHQP/RoC7jqSrQO0NMJF7m7wOX1ULL9d9yGBS70EwykBsdxQ1D5xof2p34GetWXrVtBseM1Db0ssu9EZWgvqi21djIFQVuva85YTnoXbNV8V0GdRdrls3NhBA601T0sHsCeko5qHW+96GmXtlQPfujfbByU4A1yO5QsgpFzHNZZqPfbzzBDmAuMjYpUDLhzDxr5rQk8hT9ihMImWsWA4KOFri/d10f6MRUfFKsqUbItDW5mIglDtN5v8XCQyI0AnjHU3D2W7ou8g== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=redhat.com smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=XTc+83HyaYqpRAllhCZ1EK1SMHyS3pZOvOBym1l5jYE=; b=kx7k6MT5PIErhVOIHLLho079e0iwK6J03+iwteC4JwA46Dnu5AdnoOzRHKSSiat8Y+03Mg1viiP8Alm5NHlUIN0ushCaa5Y4gcOg/l1ECfLaXwvwe8lSGVsz2KupjVnnewttEEBPuw9FIXy/34us+6+IiDG/km5A0URwWrLLUb0= Received: from CH0PR03CA0269.namprd03.prod.outlook.com (2603:10b6:610:e5::34) by MN0PR12MB5737.namprd12.prod.outlook.com (2603:10b6:208:370::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8511.17; Thu, 6 Mar 2025 15:33:25 +0000 Received: from CH2PEPF0000013E.namprd02.prod.outlook.com (2603:10b6:610:e5:cafe::b1) by CH0PR03CA0269.outlook.office365.com (2603:10b6:610:e5::34) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.8511.19 via Frontend Transport; Thu, 6 Mar 2025 15:33:25 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by CH2PEPF0000013E.mail.protection.outlook.com (10.167.244.70) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8511.15 via Frontend Transport; Thu, 6 Mar 2025 15:33:24 +0000 Received: from [172.31.188.187] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Thu, 6 Mar 2025 09:33:19 -0600 Message-ID: <39574d99-51a2-4314-989e-6331ca7c0d75@amd.com> Date: Thu, 6 Mar 2025 21:03:17 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 3/3] treewide: pipe: Convert all references to pipe->{head,tail,max_usage,ring_size} to unsigned short To: Oleg Nesterov , Rasmus Villemoes CC: Linus Torvalds , Miklos Szeredi , Alexander Viro , "Christian Brauner" , Andrew Morton , "Hugh Dickins" , , , , Jan Kara , "Matthew Wilcox (Oracle)" , "Mateusz Guzik" , "Gautham R. Shenoy" , , , Swapnil Sapkal References: <20250306113924.20004-1-kprateek.nayak@amd.com> <20250306113924.20004-4-kprateek.nayak@amd.com> <20250306123245.GE19868@redhat.com> <20250306124120.GF19868@redhat.com> Content-Language: en-US From: K Prateek Nayak In-Reply-To: <20250306124120.GF19868@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF0000013E:EE_|MN0PR12MB5737:EE_ X-MS-Office365-Filtering-Correlation-Id: a5f85133-2085-4f76-393e-08dd5cc43c36 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|7416014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: =?utf-8?B?QVhBYXBzVmo5OXpzMUZMWjBqRDZJR2Y4NU5LdWFTbGE4Yzlvcjd3dm8rV2pG?= =?utf-8?B?cDBoNmpleEpQdksxdDRET2RFcUtCWVJhWjRQZzhjcHlyaVc1eDFTT1RxM3lV?= =?utf-8?B?bFF6Zi9tbFE1N3duS2s0WDRBMzg2dW9iVmFHNW1oZW1YcTJnaHk1RStHT3RZ?= =?utf-8?B?NnlQb1JORmFLdk4zc1hTN3dYdE5tRnVudk00Z1Vzb0p2SUpMMWFCeEtkYjlF?= =?utf-8?B?R3RYQjNwUHhBaEsvU25rcFh0bUVVMElHWTF6M0NzUzFVbHZkb0RyQzFOUzBR?= =?utf-8?B?MnpadFFMamh0TGM0TVY3NE41c2c3V25YUWEySG4rYUEyalhiUVBUUW01MGFO?= =?utf-8?B?NGZnODlJUmdVQXU0Y0lUWUVjTkNHTTFCQXRldi84NklIQzNHRzhpVTZmNURN?= =?utf-8?B?eDZQUnZtaG1wR3UzSnFiS01WcElSeTJJNTJ3dzRQZjdETWtvbk1QZ0NGdzEw?= =?utf-8?B?cG9XcUQ1UUVwdjYyZlRDVUpwd3hwMjRRMnBLQmlERnlxRDNBUEJhN2ZpWEd6?= =?utf-8?B?ZDE1OU9VdGtZUWozaTZJNVhBT08vT3pwaldXZWd2ZHkyWDNNUFM0TlR4cEhV?= =?utf-8?B?OWdrQjZPTWVMWDNKL2hJTVFnNGtObGZldWVLd3JWSFRWQWY4RkppcGFUUE50?= =?utf-8?B?NXR4ZUVQemc2WmN5YzNuZkowQ2wySXZxMmEyREVHS213bmdKZTVMQzZ5MG8r?= =?utf-8?B?NWQ2c0dHVVBYT1hCeGpBWis0QS9namppSWg2bGdVYWNwZWtTZmxJY1haMHJv?= =?utf-8?B?b0hMVWZqR3E0cEY2ZUN0TWZUc1IrSHczVkZMZktVc0R6clNhVUxsU1pjdEFZ?= =?utf-8?B?L3pqWTduZ0V6Ti9nTHM1TTQvbmYxUUhsdXNETG00SFlUNXBLeDV4cjBwUnNu?= =?utf-8?B?VU41clRxZmZrenNMelduRW5qallBV1krVkFPVDhKY2E5T3lJV2dsdUJvT01B?= =?utf-8?B?YW9BVWxDTTdVdEVscHNwWXA3S1l1dFQwUlhsUFQrU0VCZEY1MnFpRWVvOGhB?= =?utf-8?B?ZkVES1lnSDZHRG9kVFI0MlBSYnpKK3dxTmNvcENOOGNtdnhzSkdOay9PSzBk?= =?utf-8?B?MUtTdnB4QitmaTZDUnhVMmVHU0dzcWVMMkcvcHNRWkFjV0V3bkg3RWlxZFA1?= =?utf-8?B?SzdlRC9EdVN6UVdjanVuS3BEYnh2MjRpR0R1MmFPcU5NREZ3WnVMOURhOFR6?= =?utf-8?B?a0tNN0ZqdFFMU28zY0FteFl3OU9Vd3QyenJaL0NXRTltU0QrdWtNNjVPNFB5?= =?utf-8?B?aUJMWGxhYlFzcWtPYUMxSm4raUQ5L1lxTnZHa01Xcm5CU1IxVDBZNnFIWXcz?= =?utf-8?B?TTJEQllsS09TUTZZYXZyZnI1QW9VdC9DUWYyMW5YU1pqNnZxSzVQY21oZ1VZ?= =?utf-8?B?dTJSRE9tQk4yRnpINndZcS9lQU4vWGpJeUxwbW1sS3A1UjJEbW13OTZJMlYv?= =?utf-8?B?RUpSdFhtaGhCeHVsem9Da1ZuNVFwVWk3NktwRitPY2VWZ1VadTMwTGVEekkx?= =?utf-8?B?WlcxT0xmUkhQWnArbGlYcVg0MkxqRHdGMHcrZlhMRzJmNlhnMEZEajJZWWhV?= =?utf-8?B?MzBEa3QwNkg3bDRCU0VZM0Q3R0NZWjFVUTVITGpZbURvamhwU3RkVkJnZkNo?= =?utf-8?B?Sk1ucXVuQmdqY3Ztd3VyaXhNN0h2SmhvaWhYSmdWdU9QK0R6QS9ZZFJGenZj?= =?utf-8?B?aUVBbTNPZXFmQzJZTjF1UWptQlVJdFc5T1JZZjE3RWhtRkVWQmM0ZkdIclFO?= =?utf-8?B?UExsUFJQcXovdWtsMUVUWm1SejZpYTZiNWJiNG4wbGRTdkNSZ1lUSzc0TTY1?= =?utf-8?B?aUJrMGEya0ZlaS9VL0lITEMwMFVHMVY0TlRBY0FxWDZjekpuNk0wZ2VRVkpB?= =?utf-8?B?U0lqRWVBMStHalJndlNBbGZPcHpwSzVkSGFHWUxTMm9MVEhqOGx6NWRKOFRI?= =?utf-8?B?VUxwUThUbmw0SHlaeGQ2OWRXeUhEZGhzbUpkSUhaZ2tVeWtrQ3BKOC8vQjhv?= =?utf-8?B?ZGU2YmJXN0h3PT0=?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(376014)(7416014)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Mar 2025 15:33:24.9386 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a5f85133-2085-4f76-393e-08dd5cc43c36 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CH2PEPF0000013E.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5737 Hello Oleg, Rasmus, On 3/6/2025 6:11 PM, Oleg Nesterov wrote: > On 03/06, Oleg Nesterov wrote: >> >> On 03/06, K Prateek Nayak wrote: >>> >>> @@ -272,9 +272,9 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) >>> */ >>> for (;;) { >>> /* Read ->head with a barrier vs post_one_notification() */ >>> - unsigned int head = smp_load_acquire(&pipe->head); >>> - unsigned int tail = pipe->tail; >>> - unsigned int mask = pipe->ring_size - 1; >>> + unsigned short head = smp_load_acquire(&pipe->head); >>> + unsigned short tail = pipe->tail; >>> + unsigned short mask = pipe->ring_size - 1; >> >> I dunno... but if we do this, perhaps we should >> s/unsigned int/pipe_index_t instead? >> >> At least this would be more grep friendly. Ack. I'll leave the typedef untouched and convert these to use pipe_index_t. This was an experiment so see if anything breaks with u16 conversion just to get more testing on that scenario. As Rasmus mentioned, leaving the head and tail as u32 on 64bit will lead to better code generation. > > in any case, I think another cleanup before this change makes sense... > pipe->ring_size is overused. pipe_read(), pipe_write() and much more > users do not need "unsigned int mask", they can use pipe_buf(buf, slot) > instead. Ack. I'll add a cleanup patch ahead of this conversion. Thank you both for taking a look. > > Oleg. > -- Thanks and Regards, Prateek