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Thu, 29 May 2025 11:06:42 -0700 (PDT) MIME-Version: 1.0 Date: Thu, 29 May 2025 19:06:31 +0100 X-Gm-Features: AX0GCFuLx1ebg1um-Wvw2yLKxLULT9vBQmKSGIdGNhtG4ZD2f7z9axswg2Z8rqk Message-ID: Subject: A question regarding isolated cpus and software interrupts To: lttng-dev@lists.lttng.org Content-Type: text/plain; charset="UTF-8" X-Mailman-Approved-At: Fri, 30 May 2025 10:21:58 -0400 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: David Aldrich via lttng-dev Reply-To: David Aldrich Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Hi My question isn't directly related to lttng but I would welcome some advice. Our Linux application is showing 'blips' whereby there are occasional increases in processing times. This is for a user process that runs on an isolated core. Using lttng and TraceCompass I have found that the 'blip' sometimes coincides with a TIMER_SOFTIRQ event on the isolated core. I was surprised that software interrupts may run on isolated cores. Is there a way of preventing this? Are there any techniques using lttng to gain more information related to the interrupt (e.g. what is causing it)? Best regards David