Received-SPF: pass (google.com: domain of linux-kernel+bounces-169942-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Mon, 6 May 2024 07:04:03 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: fuyuanli <fuyuanli@didiglobal.com>
Cc: <mingo@redhat.com>, <peterz@infradead.org>, <juri.lelli@redhat.com>,
 <vincent.guittot@linaro.org>, <dietmar.eggemann@arm.com>,
 <rostedt@goodmis.org>, <bsegall@google.com>, <mgorman@suse.de>,
 <bristot@redhat.com>, <vschneid@redhat.com>, <kolyshkin@gmail.com>,
 <akpm@linux-foundation.org>, <kent.overstreet@linux.dev>,
 <frederic@kernel.org>, <oleg@redhat.com>, <hca@linux.ibm.com>,
 <paulmck@kernel.org>, <tj@kernel.org>, <bigeasy@linutronix.de>,
 <CruzZhao@linux.alibaba.com>, <pabeni@redhat.com>,
 <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched: Introduce task_struct::latency_sensi_flag.
Message-ID: <20240506070403.181b574d@kernel.org>
In-Reply-To: <20240505030615.GA5131@didi-ThinkCentre-M920t-N000>
References: <20240505030615.GA5131@didi-ThinkCentre-M920t-N000>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

On Sun, 5 May 2024 11:06:15 +0800 fuyuanli wrote:
> A test has been made in two hosts named A and B. In A, several clients
> sent udp packets to a single server in B concurrently as fast as
> possible. In B, the IRQs of these flows were bound to CPU 0 by flow
> director, so there was always a triggered net_rx softirq on CPU 0. Then
> a test program was started in B, which was also bound to CPU 0, and
> keeped calling sendto() in a loop. Sampling with perf, results showed
> that about 25% of running time of test program was spent executing
> local_bh_enable() contained in syscall sendto(), but after setting
> latency_sensi_flag to 1, this proportion had been reduced to 0.5%.

Enable threaded NAPI, it will have the same effect.