From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 605CD56758; Tue, 5 Mar 2024 11:35:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709638533; cv=none; b=AUG67DE71G+eb2ogH+3QQG3ewpnK1q8Xbm3/g0r44hc+jXW2giudanVXD0Dh66QCS/wxXzY01uehkgrNf+oPp2lWc28btQHrDBJYUKHakmk/SmCha8euBfUDjP8VYC6qopQEv4A6P5zLcsqQUKLjWsyGqV4TL9/nbSPeXs4YAwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709638533; c=relaxed/simple; bh=1pWSWqjFhvRKTLbt/RaCTa1L9MzH/peD1nMCCxEnHZw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=R2fW3u3qWEOMc06SXYny/Ne2d+xGB+20qiXSz6SIulhGjY+6ezAlKqqjZGSnzhfKVUCh8/FVsWr2733AwgZsPAhRvnLPLfjARr4QwjSJxH4tfSEwAerfmNTiKx7llTOGh6TtlgLVXSSJpWhCyAp6SNHbo3kYatR1469Ci91jWKM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qyMSuYbS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qyMSuYbS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EA48C433F1; Tue, 5 Mar 2024 11:35:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709638532; bh=1pWSWqjFhvRKTLbt/RaCTa1L9MzH/peD1nMCCxEnHZw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qyMSuYbS9nx58vLVK+66V/99HS0zzw1qb/O4yaIqTItM19PP8lmPwpDpu9Z3KOgan naW2DICnOAOjZ6vy+ZgD/NkiM3+IGrtb+BUjNGsi/hDBKsEe2ZMuuUOAaPdY303M7d H/H+Qsg417fpmjQJeSOuCIP86wWs2iT3nnEmFwro3gfMq9dw94kJ1bppXdhkTM707F JFtL/XlDsmGS4XpQOP562UEuqI6wk+jsXOGNM3CcC1T/k7E7KfhDBSImxEY8r6BUzp IwHprECZJ+Q+e2Xr1nl7FrIeWwAHuEiYcAa0j7iOCEm3WlOAP3jTWtl86Vovmkz4iJ hoIcMyrwC6xag== Date: Tue, 5 Mar 2024 12:35:30 +0100 From: Frederic Weisbecker To: Oliver Sang Cc: Anna-Maria Behnsen , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , ying.huang@intel.com, feng.tang@intel.com, fengwei.yin@intel.com Subject: Re: [tip:timers/core] [timers] 7ee9887703: netperf.Throughput_Mbps -1.2% regression Message-ID: References: <202403011511.24defbbd-oliver.sang@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Tue, Mar 05, 2024 at 10:17:43AM +0800, Oliver Sang wrote: > 20.97 ± 3% -9.7 11.23 ± 16% -9.6 11.40 ± 4% perf-profile.calltrace.cycles-pp.__napi_poll.net_rx_action.__do_softirq.irq_exit_rcu.sysvec_apic_timer_interrupt And yes, fewer time spent in IRQ-tail softirq processing. > 1.70 ± 13% +5.6 7.28 ± 14% +5.8 7.54 ± 15% perf-profile.calltrace.cycles-pp.__napi_poll.net_rx_action.__do_softirq.run_ksoftirqd.smpboot_thread_fn And more time spent in ksoftirqd softirq processing. This can match the increase in involuntary context switches: IRQ-tail softirq processing takes too much time, possibly due to long lasting remote timer expiring, ksoftirqd is then scheduled, preempting netperf (through might_resched()/cond_resched()) as this is a voluntary preemption kernel). Thanks.