From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 0DC022472B6; Thu, 6 Nov 2025 17:31:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762450297; cv=none; b=auJh9TzPoDSN/I74SGWh9KLeHNUDQbnFJ/tnJWifxFTiwrdTmqMSpHDPiZJSUSUeTAc7b27DCBZrJsPzhOLtGtXEOmUYrZDN152HvFc31Bv0j32tvWZuGvoxBjkzMsIlUm3bg2ue85F57c/ObW8bJM7UANkh63+evzDWr5OVUw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762450297; c=relaxed/simple; bh=5WD5BNzh1FuLBmayQkd/a08wH4PFBEuUidQyNtpNXw4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=UGc86dehtvBaCCqyfShd4GcXSV9voG7/qrDE7sqp/K7J5CTets08nt+q3V/nT2t0RyrFgycZNM9bTjy0NVrXSN88Hrf9vIL9abf76TU7uwpIOgFqFsyGLt2TpwjWBChnqI39upv6a75QgNxK/qWelyYkkw5dI+4uyshFB7w7PVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=XyvD74Es; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="XyvD74Es" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1762450295; x=1793986295; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=5WD5BNzh1FuLBmayQkd/a08wH4PFBEuUidQyNtpNXw4=; b=XyvD74EsmjJBB/PfWUSxroZ/ooreMj9Vq4yHEGepcuYKmOO/mrcluWrx YJJ4vP6apRQ/6lF5T7jvI9XmAcoTqfh+EpA87FjSwV5seQFex87ke1/mv RO93TDjFU1rAcQDnWyc+bOTas3SRATNqVJem2B8+/fKMHTKaPuhBMP6XT CSI8Z1N55kU6O30yoO5YBq0yrN3K7pX4GewgM3NZMkewD9+pCnDmNU4xV yJHn4PNJqwooc1c86zoWF5ALQdZ3BQqa3eb7CJqrkym064UdKdzkfIMHo fmCbdzZ304ygLnQJYGpwynz5EsDVUpYTDtI2QpF5jVWEE1iiFasoJMBG3 w==; X-CSE-ConnectionGUID: TT92YGZcSzeaSgU9SGlgqQ== X-CSE-MsgGUID: o01eyOGAT3mk9jIPmEiQ9Q== X-IronPort-AV: E=McAfee;i="6800,10657,11604"; a="63608577" X-IronPort-AV: E=Sophos;i="6.19,284,1754982000"; d="scan'208";a="63608577" Received: from fmviesa009.fm.intel.com ([10.60.135.149]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Nov 2025 09:31:34 -0800 X-CSE-ConnectionGUID: oY3JpO6UQ4KxGh176TtY1A== X-CSE-MsgGUID: dIPLHy0CTlmHM8IpPX6iaA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,284,1754982000"; d="scan'208";a="188256663" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.54.38.190]) by fmviesa009.fm.intel.com with ESMTP; 06 Nov 2025 09:31:33 -0800 Received: by tassilo.localdomain (Postfix, from userid 1000) id 8744130170C; Thu, 06 Nov 2025 09:31:33 -0800 (PST) From: Andi Kleen To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Adrian Hunter , "Dr. David Alan Gilbert" , Yang Li , James Clark , Thomas Falcon , Thomas Richter , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Dapeng Mi Subject: Re: [PATCH v3 9/9] perf stat: Add no-affinity flag In-Reply-To: <20251106071241.141234-10-irogers@google.com> (Ian Rogers's message of "Wed, 5 Nov 2025 23:12:40 -0800") References: <20251106071241.141234-1-irogers@google.com> <20251106071241.141234-10-irogers@google.com> Date: Thu, 06 Nov 2025 09:31:33 -0800 Message-ID: <87cy5v3w5m.fsf@linux.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Ian Rogers writes: > Add flag that disables affinity behavior. Using sched_setaffinity to > place a perf thread on a CPU can avoid certain interprocessor > interrupts but may introduce a delay due to the scheduling, > particularly on loaded machines. Add a command line option to disable > the behavior. This behavior is less present in other tools like `perf > record`, as it uses a ring buffer and doesn't make repeated system > calls. I would rather use a real time scheduling policy instead if you see starvation. That would still get the batching efficiency. If it's done it would be better in .perfconfig instead of adding ever more obscure command line options. -Andi