linux-kernel - Re: [PATCH] sched: Introduce task_struct::latency_sensi

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Message-ID: <6E852CFB-3D1B-4A3B-AFCA-8E0717DE343C@didiglobal.com>
Date: Wed, 8 May 2024 03:02:49 +0000
From: 付元力 Jerry Fu <fuyuanli@...iglobal.com>
To: Jakub Kicinski <kuba@...nel.org>
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Subject: Re: [PATCH] sched: Introduce task_struct::latency_sensi_flag.

Sure, my first thought is providing a way to have a
low-latency task if user does not want to enable 
napi threaded. Once it is enabled, which will affect
all system. I want to have a low-latency task while 
minimizing the impact on the system.

Thanks
fuyuanli

在 2024/5/6 下午10:04，“Jakub Kicinski”<kuba@...nel.org <mailto:kuba@...nel.org>> 写入:


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.