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Date: Wed, 26 Aug 2020 09:45:58 +0800 From: Feng Tang <feng.tang@...el.com> To: "Luck, Tony" <tony.luck@...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>, Mel Gorman <mgorman@...e.com> Subject: Re: [LKP] Re: [x86/mce] 1de08dccd3: will-it-scale.per_process_ops -14.1% regression On Wed, Aug 26, 2020 at 12:44:37AM +0800, Luck, Tony wrote: > > These 2 variables are accessed in 2 hot call stacks (for this 288 CPU > > Xeon Phi platform): > > This might be the key element of "weirdness" for this system. It > has 288 CPUs ... cache alignment problems are often not too bad > on "small" systems. The as you scale up to bigger machines you > suddenly hit some critical point and performance drops dramatically. > > It's good that you are picking up tips on how to bisect these and diagnose > the underlying problem. Number of cores is going to keep increasing, so > we will keep finding new issues like this. Yes, now we have one more bullet for shooting this kind of strange performance changes :) Thanks, Feng > -Tony
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