linux-kernel - RE: [LKP] Re: [x86/mce] 1de08dccd3: will-it-scale.per_process

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Message-ID: <149e0cfb5b7e48dfb9bea966c7741336@intel.com>
Date:   Wed, 19 Aug 2020 02:23:11 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     "Tang, Feng" <feng.tang@...el.com>
CC:     Borislav Petkov <bp@...e.de>,
        "Chen, Rong A" <rong.a.chen@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "lkp@...ts.01.org" <lkp@...ts.01.org>
Subject: RE: [LKP] Re: [x86/mce] 1de08dccd3: will-it-scale.per_process_ops
 -14.1% regression

	0000000000019260 D pqr_state

Do you have /sys/fs/resctrl mounted?  This variable is read on every context switch.
If your benchmark does a lot of context switching and this now shares a cache line
with something different (especially something that is sometimes modified from another
CPU) that could cause some cache line bouncing.

-Tony