From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2B38C9832A for ; Tue, 29 Sep 2026 15:36:17 +0000 (UTC) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 46D8040ED8; Tue, 29 Sep 2026 17:36:16 +0200 (CEST) Received: from mail-pz2-f39.google.com (mail-pz2-f39.google.com [74.125.228.39]) by mails.dpdk.org (Postfix) with ESMTP id 2239140679 for ; Tue, 29 Sep 2026 17:36:14 +0200 (CEST) Received: by mail-pz2-f39.google.com with SMTP id d2e1a72fcca58-88103e47f72so3013800b3a.2 for ; Tue, 29 Sep 2026 08:36:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20251104.gappssmtp.com; s=20251104; t=1790696173; x=1791300973; darn=dpdk.org; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=KKrAiIdZC6pGEMv8MNbAUpgyXkr+4weUDfj0Qj7r+EM=; b=RQccwLctHWJfD8cNaFMeexEU59NlOcJK2AaNpxyvrK6c2eeQN2wlXqhUonbjeimSVk F3RB7ENpmLgAJZM4zRD/lcgvXGdv6cibL3H2Hzd19RtuyDguWGWIWNsQKwaMmAzKwCJq 8/L4IIo/oI7PETnQWbe7nI29bllQ9n6f0PSOHeAnd7HyHurmnFvFUAXKBeZDcSrWaMuR GUbgQnX7bMxJdgEsDabVbevG3bq2HS37RB9czrU7WtzTEgzNk9XXWiO+1jyO4ioI0H4S 9xR9OFvkeeKOk5ujaH5YnVAw+cEjnyG/D6zPlfrXadSvqUZxxR28j/BEPCEsvyO91iic phpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790696173; x=1791300973; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=KKrAiIdZC6pGEMv8MNbAUpgyXkr+4weUDfj0Qj7r+EM=; b=Od4IZfP9imdKbSeOoWXxP8maRa0Tfb9CzdECaPuxTMeZl7VnzRjQjnLW4pW4/zPOoo FL/Xi0PRue/y5xC/4QLGnnXO3/My7v+5ARRknXK4VcBsK1at7EZ5PY516TeKLIWGopYo ilHiQqYSHOhKoljmvhpA1xYi7LD2UOCwsWd/b9H66zitIuaaub/kcAcC2Wzc/10fDnsr qCi+8qB7r9B3ihPjTOlKfEQ0FDjHjhLN+kuksIypecRaPyCTtMLjx+YqqofCKrV7q9f6 5/6FeUGbKJBy6vSlqEOk8RG+frCgBjrTPAg7RXT0BSSthsrJFJjATEar2uN9XVNZNZcH 4tAA== X-Gm-Message-State: AFuF++muA5aAy/ryedliBV/0CdXEuo/NxlOrmahakGqITuLW5tf6TUHj ywSjiBv5YV0IdoqPEA0Sh2sbb7S5UDdO0bootBVpExa2wV0JDcgFJ410ASsEZ7bvsJIo8aIGWfw Xt1FnIGg= X-Gm-Gg: AYBFou33D4vulEVXpjPqwd7wolmONqNj2+d9M54jR5JYqMbvEcMnZ0cgQRR3eFlObGA 7fp+qB332MWZ4jPPycCGjVEgH2/tRERhkIFCOhRQ+KWXcFLLOZeLPUC70X1C7ayMmGA86NDH63U MBTBk4NX8UyeP7mNuxTKOd5nKJdsBqyVVgxT0BB5lnQ8wxvjThp15cYM8548yYlOp5TOS8afybo p299r0FpdnvGJhUSbJcRMhW7qoJhZn+/HBjiPoByvsWqz+S0R890keUj54fqBdcY0q55lzhL8kq lAthKB7XqyOtW0hq1K198z3UE0Lxz19z0NbwdSFvPvyxOmmIo8x7kPFbiFSMbZ89LysDYYgqLoM foPTVljUJFru0tPHLae9vO/TizOOQdhYL5Y4dWY44tAzxCAFz04FOSZ3rEhgnx1u9VUKhFi6D33 tdGL4Sf87P5Ms2jV4qrTJW1cMuAby4yUzgi9ZdY4wP229rQ7A3qekOXW9PTzRdOvOXICEAJ/pxe IFweFRROFSDVYWWkC9ZHuVzAMgssgJiFzcBu5gg X-Received: by 2002:a05:6a00:909f:b0:882:23ce:f515 with SMTP id d2e1a72fcca58-88223cef818mr7334298b3a.33.1790696172936; Tue, 29 Sep 2026 08:36:12 -0700 (PDT) Received: from phoenix.local (204-195-112-43.wavecable.com. [204.195.112.43]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8868865fee5sm173065b3a.6.2026.09.29.08.36.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 08:36:12 -0700 (PDT) Date: Tue, 29 Sep 2026 08:36:08 -0700 From: Stephen Hemminger To: dev@dpdk.org Cc: stable@dpdk.org, Reshma Pattan Subject: Re: [PATCH 1/2] pcapng: revert use of reciprocal divide for timestamps Message-ID: <20260929083608.1da61ca9@phoenix.local> In-Reply-To: <20260927195015.78109-1-stephen@networkplumber.org> References: <20260927195015.78109-1-stephen@networkplumber.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Sun, 27 Sep 2026 12:50:14 -0700 Stephen Hemminger wrote: > The use of recprocal divide caused in calculating timestamps > caused overflow wraparound. This bug was introduced by confusion > about bits, shift, and the test was too short to catch the > problem. > > Go back to just doing the divide which ends up faster on many > than having to do 128 bit math on many CPU types. > > This is not a pure git revert because there were other > good things in that commit like handling earlier packets, > and catching if TSC hz was zero. > > Fixes: 4fc65615b274 ("pcapng: improve performance of timestamping") > Cc: stable@dpdk.org > > Signed-off-by: Stephen Hemminger > --- Both applied to next-net