linux-kernel - Re: [linus:master] [x86/bugs] 6613d82e61: stress-ng.mutex.ops_per

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Date: Mon, 4 Mar 2024 09:58:53 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: kernel test robot <yujie.liu@...el.com>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: oe-lkp@...ts.linux.dev, lkp@...el.com, linux-kernel@...r.kernel.org,
 Dave Hansen <dave.hansen@...ux.intel.com>, kvm@...r.kernel.org,
 ying.huang@...el.com, feng.tang@...el.com, fengwei.yin@...el.com
Subject: Re: [linus:master] [x86/bugs] 6613d82e61: stress-ng.mutex.ops_per_sec
 -7.9% regression

On 3/3/24 21:53, kernel test robot wrote:
> kernel test robot noticed a -7.9% regression of stress-ng.mutex.ops_per_sec on:
> 
> commit: 6613d82e617dd7eb8b0c40b2fe3acea655b1d611 ("x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

This _looks_ like noise to me.

Some benchmarks went up, some went down.  The differential profile shows
random gunk that basically amounts to "my computer is slow" because it's
mostly things that change when the result changes, like:

>     182670            +9.0%     199032        stress-ng.mutex.nanosecs_per_mutex

Does anyone think there's something substantial to chase after here?