From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from YT5PR01CU002.outbound.protection.outlook.com (mail-canadacentralazon11021138.outbound.protection.outlook.com [40.107.192.138]) (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 7804C1D9346 for ; Mon, 16 Mar 2026 13:53:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.192.138 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773669195; cv=fail; b=DSXtjOWd3PJbM/sxEok2Gg+1lLRHbqvXWpvlyubm9c8KKUr1UeEn8qy4Wq8XVPq0Oa3iTAilK6LLAroUWuJT2qtJeJqkFZEsdRLUabD3ttYzKjOI1ua3O+uwht6VIuDojGFC3PwDScS2iLC0PMhPkRe/vl+0RbRK3xaqPQjTiP0= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773669195; c=relaxed/simple; bh=Wx3HNIydfrShUH5m4XmeBBQh8QnuGo8tWK5cvDbqgOk=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=WK74AGHVCsSgdsCKRMEBaDuNpSLI/CbejBrxkB66mG12NMcaIby4XAISIYeOS+VvdMT0RYy4rCKAwzwKxygCBqjpF1S+ZKt6D1inQAVBwHBkOy5stJ0KF0wO5M6IKetZUaM4ddqFPiiZWotZPp6y1iaWXOzKraxlnWZVz1ge2h4= 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=CPSkv1zh; arc=fail smtp.client-ip=40.107.192.138 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="CPSkv1zh" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=gNrCCTs77dY/V5/BcjWS5bIVsdgnIpA7kjz+YrgXqYjPmd7qJhGttpKAnL6+sQis1EBcyl9q7WC+kGE8tvFYHY+2PsoxIBuG0xk6chVutTUOUT5jzSf6z6s9HjQBrzUDSXuRFy6H9QpVUB+65WoVTTZirPkqSsUOfLkAx/VTApZCxcNxz9dMPTB0UnSh+JVtQ65VvY8BoyjLt1kyVeT53A6ymolDdNBCKXU6SSYi0MYuSm+MD4rD3+dVEx8Z6Pb33Xlwy9x5t60cROhQwSIM0PVJJZYEVUj2/RZjCfZDesenNagMOyT1iDcrwaw322S36xjm1Nq7uWJ2yReKzwmJvQ== 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=n+zpUWygxg1duNkA+qdpGmAY2OqQt4gr4c3oh/hlDGI=; b=t9xzQCNqczRLD4o8KJuZPDmhi0uhcaowYcOtZkp3q19MGjLARmGs04NtTicuAOgUDApQhguGhJ83x/wgRWbrRGEUqQ/W7t8Xg24wu49Die0Gp/jA2YdcVdJvGneqv9IKDwuhPpaamObd/gKk9vJfD2ud7zpYKynlTX4uv+poDbj3mrrjsYYMJdHOt2RFMvOlzWUm/D3OaFFvDY/FNWsNShMs2Joeq88FOKdIhEpLAxPYeqMMQhBuEpTMLmdUDR8mBO7cwioXELVR86vzmKQUar2mn/Cmocj963kn/jeeeP3jMaSx+pRNojTOsk4BxUOgQcTxNI98MBh5LRtRRpzZCw== 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=n+zpUWygxg1duNkA+qdpGmAY2OqQt4gr4c3oh/hlDGI=; b=CPSkv1zhhXIK1Nr2RaaUQ1MpsimGFWEdE/RBmdbfq9FfHNaDNA3afi9pr6gMZYer36minDNbzZiMPXR0dmpTOiUcvuNEPA66YhVD7f/FeOg6RseWxYVVUTco+XFSDgTW1ji3/BJsaBb0/AWGsl2Kio6OLjcT9vW5rUIBw7+jXz+1EDIb0r0FuGLQ7yxDghse4AKC/0SPSsrMqL6ngC1H93RSiGYhAK4RXOSfcCkkLeYFQQtdj/GZkLaugrVFKxlFNxjw5x/V35xseFHpnHhPtF/MXRWpHWM15xLNXzVDmlF7tIQ0wU9eJovg6ym6hjEOgPBj96UcmHR37k0YuU6SEA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=efficios.com; Received: from YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) by YT1PR01MB9403.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:aa::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9700.25; Mon, 16 Mar 2026 13:53:01 +0000 Received: from YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM ([fe80::6004:a862:d45d:90c1]) by YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM ([fe80::6004:a862:d45d:90c1%3]) with mapi id 15.20.9700.024; Mon, 16 Mar 2026 13:53:08 +0000 Message-ID: <5134efe0-e780-467b-9289-fe5e4f7aebca@efficios.com> Date: Mon, 16 Mar 2026 09:53:05 -0400 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] lib: fix compare_delta parameter order in percpu_counter_tree To: David CARLIER Cc: Andrew Morton , Josh Law , Dennis Zhou , linux-kernel@vger.kernel.org References: <20260313175424.132735-1-devnexen@gmail.com> <20260314144508.ba3504b4338eb1ae84017028@linux-foundation.org> <65bc70e0-c9a8-44b7-aa8e-3ffa31b0ed75@efficios.com> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: YT4P288CA0048.CANP288.PROD.OUTLOOK.COM (2603:10b6:b01:d3::25) To YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) 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: YT2PR01MB9175:EE_|YT1PR01MB9403:EE_ X-MS-Office365-Filtering-Correlation-Id: 51d3d1e1-e6d6-4dd1-ca79-08de83635a41 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|366016|18002099003|22082099003|56012099003; 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:YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM;PTR:;CAT:NONE;SFS:(13230040)(376014)(1800799024)(366016)(18002099003)(22082099003)(56012099003);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?VVcxbWtDOGRyNTlFZGlUYVFlcGxUZXZnRTNPaXc5RUszNm9kaGlsOEFGdFFF?= =?utf-8?B?cnh0MFZ5NlpGSWxEblowZ3ZwK05ackoxMi9YTXZ4WVMwd01kNmtoRFE5ZGNL?= =?utf-8?B?S2lQNFMrdjNVbms3dkNpUkdNdHBoUGJEdnFWY2pvVHFPN04xZnViM1IwZElj?= =?utf-8?B?Umsyc2xOekVPYzBzeXRmRlRDQUYyUVlYL1pWZmU1RS8rcDBHWVBCOCtPcytk?= =?utf-8?B?SkJscjQ5SkNSNHBGNlZxWlI5d0RjR0IrNnVWM0JyKzZMbW0wb0s1bklHWENo?= =?utf-8?B?U20zSUlUaWFEOFVmckpLWXM5c0tPZGsxazFWQ2NFc2I4VFgxa3ljSlNwVDl3?= =?utf-8?B?b3UzQTV4S3gvR3p4TThxUCtwaTBIYUF3ZEhacHh1MlovdjhsN1FjNVVlTmhh?= =?utf-8?B?L2dSNmY5ZHFIWVp4T3lURmlzeno1R3JJejk5dXRrTTBXSmljOHJpMGVNN09m?= =?utf-8?B?Ui9KQkYyZWlyWm1MTnVvMGhUMjhhM2thVkRiYlRYcWFrZWp1QXY3U1BJdFBa?= =?utf-8?B?N1E1VHQ0RGFsb1VUclAzY1pmNDhNYzRQZDA3Zk1PSGtzZVZ6eWRzVjhxNHll?= =?utf-8?B?NGU1YWZpL25NRkpZcStNSlpoZjY4bXVWM3pZRGNtMHI0bFJSUzVVeFFuTmdr?= =?utf-8?B?S3pqcEpnU3RwMHE1T3E4NW8xNHJLcnFCeUE1MnRQRFluN1Vnd1JHYVA4OElC?= =?utf-8?B?cjdWZ00rMFFIME1KbHQ2Qkx2UFMrcUNiMmNYaFhSWHZZVk0vQjFKQ0lsaEwz?= =?utf-8?B?VElmb3YxVW12OEsrZFpSN25GNXdFS2lVUkpRS1dSWkZJSVVkYTZxVGlhMHpL?= =?utf-8?B?aDRGZ3czM21TZzJVV3Nycmg2ZDM3eHVXcHAyZ3hVTHBzbnRQN3ZHdUZHYzZr?= =?utf-8?B?OElKdTFnV0RENmZKdGIyWW9vS3VMaFFndUlzL2g1VUY5RWQ0eUdwcDFaQWtm?= =?utf-8?B?dG4zZlYwbmJGMEVpMXo2ekdFVjkzV01SdThGc3ZPZjhXWXdGV2Y5NDhyR0V4?= =?utf-8?B?R3h5RFZoRm8vWVRGSDBpVTdFMjA2aWVvdFB5V05XY2dPUUlYZm94a0I5SSsv?= =?utf-8?B?WHFVUXRyR0s5U1k0VUY3SWlTb0dhbW45R0NZRDZteUd3b2J5WmhsNVd1WXhl?= =?utf-8?B?ZlFZb2FqVytGMFg0emNWbVhRZ1lNMCtEYm1VTTJGcEtXa3Z5ZG5XZ1h0ZGtZ?= =?utf-8?B?RGVaMHNwUFM1ODJoKzQwSTBJUkZQWE04SVRLSlJka0p6KzczVklNU2x6WnVD?= =?utf-8?B?OW5jR3NEc2ovQmxnNW45RFBjbnphSnliOW10WHBwbjJVWUplYndCZUhHMkg3?= =?utf-8?B?TVVEbWFVRkVsRTh6S3pIeVRJcVQ0MWJNN2ExNkZuQyt2Sm5Ceis5SGJOVmpr?= =?utf-8?B?akJtOEJwdHQzY3haaVJPY09HRE5oOWhCYWtUcTJFS0szcUlrQUhaMk40YTVT?= =?utf-8?B?MTFuMW85N2pTUkw1YUErVzAvbGJ2NnVCZllhRlNOdXNDbGpEWnJENHJzamZY?= =?utf-8?B?MktkWlBGY1NlWW41U2ZRRTJQaHM3MFZRUHovd3E2b09LbTJjNlkrajY0dlJD?= =?utf-8?B?d0dnVjQvRlB1b2RHRHhlNXE5eXNQbUdqZnZOS3dacU1ENDdsdWhob2RDdm9m?= =?utf-8?B?V0hZbjVSTlpYcXA4SndDenVyRitmRlI3THp2M01ITVN1dXZvVWlTRmlOMjAx?= =?utf-8?B?ejNaY0FpeGRNeERjRW5DV2loQTFiMm02cHBabUFHOWx0M24yTnlHRWM1QXBC?= =?utf-8?B?cllvN2l5WVVpU1RaQ1pLUE5xMEkvSkMwQ3hJS1ZSWUFpakxUM1UyNHpYcDdU?= =?utf-8?B?SkE1aUNMVjlSK1NYOVdmZTA4cXJVN0pOeVpGcmUvMElDUUF1RnNNKzRvdjNH?= =?utf-8?B?cWgzekw1WXJJdXpCQlRjZVVDRlJQOUtmbmNXRGdhbHM5RDJuV3RhMXZrY2s2?= =?utf-8?B?UEtjREpiSzRjMXNMclhNSS9xSjlId2NKWlFqZHlDZElVTktPUldtWm54VVcx?= =?utf-8?B?bi8xSEpxNEZxVDZuVjdkSkFHS3ZnQjFJbG9CZXJuc3ZqK3R2YlVoRmE0d2Zl?= =?utf-8?B?OWo3WitQVGo5YlFwTFpmK1k1eEd0VHhITzU4OVJ2eVV2WmRGajN6bU5rWDR2?= =?utf-8?B?TUNDOWJ6YkVQRGZkK0JWSVVNZG1mR1cycWZEWG5sSEUrWGg5Y1NNN0xFM29Z?= =?utf-8?B?Qm02dzJhbHovajRPQmhLeU5LNnkya0tBcnYvcHF6dVZzZGVvVnFwY0crYmhR?= =?utf-8?B?YzRpdVFPc1BmZEVCaVlsS0t6Z0JuY3N3YldHdGhBM01MTG9GYlJiMUp5ZWlH?= =?utf-8?B?UCs2QTlKQ2VwelNPOE9xeWhPMlB0S0Z4VlZacU9pWnBNOUJtenJTaTVnM3J5?= =?utf-8?Q?hH5R4KceiIlezScJWlzSxo5sb2EJ1x2AQTDGZ?= X-OriginatorOrg: efficios.com X-MS-Exchange-CrossTenant-Network-Message-Id: 51d3d1e1-e6d6-4dd1-ca79-08de83635a41 X-MS-Exchange-CrossTenant-AuthSource: YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Mar 2026 13:53:07.8509 (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: 9Bi57HawAoT+pWXsgoFQ6HB3fCKJK/Wbv11pGi3U3I8KhiKhT/DYb7KYiAedQx0918OZkIqAXa9sqff0uF5GFw6eVQSoklTDMenPn+9qlo4= X-MS-Exchange-Transport-CrossTenantHeadersStamped: YT1PR01MB9403 On 2026-03-16 09:41, David CARLIER wrote: > Sure. For precise_compare_value, the boundary tests extend > naturally — the function must return the exact result regardless > of which code path (fast approximate or precise fallback) is taken. > > For the two-counter APIs, I noticed that the combined accuracy > is always symmetric: over_a + under_b = under_a + over_b = > (bs_a + bs_b - 1) * multiplier, so the asymmetric gap test > doesn't apply there. But boundary tests at the combined accuracy > limit still provide useful coverage. In order to do a relevant test for the two-counter APIs, we'll need to initialize each of the two counters with different batch sizes. This will ensure that the limits are asymmetric, and therefore allow more precise testing of the limit conditions. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com