hi all, [nginx]"accept_mutex on" cause 1s delay

Francis Daly francis at daoine.org
Mon Nov 11 12:18:51 UTC 2019

On Mon, Nov 11, 2019 at 11:26:30AM +0800, lx wrote:

Hi there,

>       I use nginx-1.16.0, nginx  is running on X86 embedded devices. The
> embedded device has 4 CPU, CPU type is: "Intel(R) Atom(TM) CPU D525   @
> 1.80GHz".
> When I use "accpet_mutex on", nginx use 1 secod for get static file.

> If  I  don't use "accpet_mutex on" , I can get  http response quickly.

> How should this problem be analyzed? I am a newcomer to nginx.

"accept_mutex off" is the default - http://nginx.org/r/accept_mutex

https://www.nginx.com/blog/performance-tuning-tips-tricks/ says

We recommend keeping the default value (off) unless you have extensive
knowledge of your app’s performance and the opportunity to test under
a variety of conditions, but it can lead to inefficient use of system
resources if the volume of new connections is low. Changing the value
to on might be beneficial under some high loads.

Your testing suggests that "accept_mutex on" does not help your use case.

So - don't set "accept_mutex on".

What further analysis is needed?


Francis Daly        francis at daoine.org

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