From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id lsbdHuVIUWhV4BEAWB0awg (envelope-from ) for ; Tue, 17 Jun 2025 06:52:21 -0400 Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=lists.lttng.org header.i=@lists.lttng.org header.a=rsa-sha256 header.s=default header.b=BH4Za3Tu; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id 6DB191E11C; Tue, 17 Jun 2025 06:52:21 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-25) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-6.5 required=5.0 tests=ARC_SIGNED,ARC_VALID,BAYES_00, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_REPLYTO_END_DIGIT, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE,RCVD_IN_VALIDITY_CERTIFIED, RCVD_IN_VALIDITY_RPBL,RCVD_IN_VALIDITY_SAFE autolearn=ham autolearn_force=no version=4.0.1 Received: from lists.lttng.org (lists.lttng.org [158.69.130.29]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 1316F1E089 for ; Tue, 17 Jun 2025 06:52:20 -0400 (EDT) ARC-Filter: OpenARC Filter v1.2.1 lists.lttng.org 4bM3bl2Y1Kz20F7 ARC-Seal: i=1; d=lists.lttng.org; s=arc1; a=rsa-sha256; cv=none; t=1750157539; b=IpeZH7KX16Qh6e3y6w3UY51nJg1k8KugDH1uH9NVkmU+9pZkMfgxOEdNd0y+693fjq1p izH7T/SH5ntRA894KxNBf8veWxIRnZyS0s2SI4Twb+InrAe18E/FvwDUHRCoaq7qAZQLc XW30rad9nyqnEUengrA6kLpk8tOnAi4H2r8VxO7ldXya7M7uTDbL1I/t1d8cPwYeDVLfj gZLVXybyy3L5cC9no7cW9+MMU8aSPPD78TTtEdkfSCBIqXqR493RrDcTkn2o3qaEBb1/k v6iDKiT83uTZkNvlRH4N+3LTwkqV+bsUGj/suAU9JZ+da+gsZHIi29HutDHzWACpFUg== ARC-Message-Signature: i=1; d=lists.lttng.org; s=arc1; a=rsa-sha256; c=relaxed/simple; t=1750157539; h=DKIM-Signature:MIME-Version:Date:Message-ID:Subject:To:From:From; bh=8klI4Ak9yxdA1R6pA9QG1ARfVDLKQG/kUyJjbBYkn8U=; b=oO9XjEfSFjpKqT+Xqbvny5WLiEEDy1Fr1RaduJ7VJgk4ssenXPCluALvWANMrAqWk8a7 jSUPpc+nQ5wietFqBdbv203kqyWeFhwFPtSEQCslqn1YG1p/2Lj8XFPiqP3n0GszKFr8u JpzknSRYwm7B3YbS7ZgWjMQqPWl9thUALgS/EViT+PijgkjQA2aIrytR/AgVTmLyXjYtp ibbuQcHyXSp5y8cMHVa6jcpX8/6dMZEQqi1vQBx0xZwZ2bDPiedAB3fX1c0beBjlgdhY5 taYcJl9HcvteWLgHOOKfKyyS7UCvyRKA+TPnB6RvofcQ9fMQtyKVnlXVhlsttN4OWTw== ARC-Authentication-Results: i=1; lists.lttng.org; arc=none smtp.remote-ip="::1" DKIM-Filter: OpenDKIM Filter v2.11.0 lists.lttng.org 4bM3bl2Y1Kz20F7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1750157539; bh=8klI4Ak9yxdA1R6pA9QG1ARfVDLKQG/kUyJjbBYkn8U=; h=Date:Subject:To:Cc:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=BH4Za3Tua9Xezfo3NP8P6PtizvQD59dH/XC4Ys7tU3YW8w3XL9xtVjdZU361xhmkH 3SnIORc0M6KWYAKNA0VeH1YNsbLjyR+bK402ozyXNJMlxSZZ+Rexua69PvKeHamv6f 3PaJ0eCWbOg9GMTX3s38XJQAA2YoptVfjZ5GV7KJ8hck1zj7AJcoyWF+ZwFaBg/2Mf JTAugT6733aAlC+YbOxXlpr5qhmQkStfwE4r0DNCh1Y1kuLx1GbPeJnYaQncYvI60l NgJN/H91Wnfzibpw8PmcS1hWl4cGN0yeogbXYE32WgJBExW492X85j6M7xtgIXvYTi w11WtoR4fciqg== Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4bM3bl2Y1Kz20F7; Tue, 17 Jun 2025 06:52:19 -0400 (EDT) ARC-Filter: OpenARC Filter v1.2.1 lists.lttng.org 4bM3bj08Wrz20F6 DKIM-Filter: OpenDKIM Filter v2.11.0 lists.lttng.org 4bM3bj08Wrz20F6 Received: from mail-lj1-x22b.google.com (mail-lj1-x22b.google.com [IPv6:2a00:1450:4864:20::22b]) by lists.lttng.org (Postfix) with ESMTPS id 4bM3bj08Wrz20F6 for ; Tue, 17 Jun 2025 06:52:16 -0400 (EDT) Received: by mail-lj1-x22b.google.com with SMTP id 38308e7fff4ca-32934448e8bso46520841fa.3 for ; Tue, 17 Jun 2025 03:52:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750157534; x=1750762334; h=cc:to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=8klI4Ak9yxdA1R6pA9QG1ARfVDLKQG/kUyJjbBYkn8U=; b=I/uSCO74uFxzS0l+ZcqOTvBGly1KtTT0vuJ9CxNZUVaVWps/BUS8pMKdqEcl76wS51 1oGu27jO0HLPTMtvo7gw5GBWDXdTe7BnNTcLkie7xtW1GCk4fP8epK9kuUP0FDjAqpnx y5mpZIG5bErCS8P7WJA2gfI1OV3ucx9zEVT/FRAJjUer/05V+ObBX9ipcqW5js1TPhio /AmYvXbHXowjfbvOLu9hudyQgcY3YtIU+9e2/w+cYmMgRuaICh2yld18/lCCKrccG6q2 HByEc3l6NZd2V41M/lh79k1NqT4z+skE9Rx3+V/hrS0gLZnhzstWZeUYNjiPrQmcN/4Q RUJw== X-Gm-Message-State: AOJu0Yy3eT27fT1cJCxS2uSPi97urniJponrNvOFOK6v/JDpOXrntLD8 zoTDMsP19yZ5vqGVZA6AYBSkzGBldQvhOqKNJ91JJyi2CcbivgQn40XkNxz4pfY9GDeCxyVJ4Q5 Jvz7kyrpnLCZ2k8LpF743q+glPtHIbWCgMEK+ X-Gm-Gg: ASbGncus1TRpK7Vaxbj0Z5CuBrVQmuCOteINR1BtWubS6/ddzqsEs/en05fI36oZioV nRz7UdjUFJON9XUf9aSDAHL60GSBVmmLKLHGIQx0MNVFu73ELg7WiYAL++77HQ1bosIAfgq3Lr4 xYvfUD4aB4vH4qSGgcD53dJtzduenkh4ME5aEh2YdgOEM= X-Google-Smtp-Source: AGHT+IGvevHXXJ6vG6eieA4jD5mluq222XGEvdR1cAyruhql8jY3WVTZuU88YhC8y0CxMZVDQjoFHY631/op7o1u/nE= X-Received: by 2002:a05:651c:4019:b0:32a:ee4e:56ad with SMTP id 38308e7fff4ca-32b4a5b9218mr25534841fa.33.1750157533384; Tue, 17 Jun 2025 03:52:13 -0700 (PDT) MIME-Version: 1.0 Date: Tue, 17 Jun 2025 12:52:01 +0200 X-Gm-Features: AX0GCFvFlQSfLL7Q1wUP09N_11c3licvwRvAJ16RdjA1tGwOuy2NCI-UMjycPD4 Message-ID: Subject: Re: A question regarding isolated cpus and software interrupts To: lttng-dev Cc: david.aldrich.ntml@gmail.com Content-Type: text/plain; charset="UTF-8" X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Norbert Lange via lttng-dev Reply-To: Norbert Lange Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Hello David, You cant fully isolate a core in Linux, there are some timekeeping functions that will always run (Linux needs some basic runtime accounting). The things you can do is avoiding IRQ handlers and "lazy" subsystems that depend on background updates via timer or IPI. You already do this via kernel parameters. Maybe you can look at disabling membarrier too. isolcpu just takes the core out of the scheduler, threads wont be moved in or out automatically. if you want to find out what causes the interrupts... use ftrace + kernelshark? Norbert