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Date:   Tue, 17 Oct 2023 18:56:56 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     kernel test robot <oliver.sang@intel.com>
Cc:     Max Kellermann <max.kellermann@ionos.com>, oe-lkp@lists.linux.dev,
        lkp@intel.com, Linux Memory Management List <linux-mm@kvack.org>,
        linux-kernel@vger.kernel.org, ying.huang@intel.com,
        feng.tang@intel.com, fengwei.yin@intel.com
Subject: Re: [linux-next:master] [drivers/char/mem]  1b057bd800:
 stress-ng.splice.ops_per_sec -99.8% regression
Message-ID: <2023101759-front-ember-6354@gregkh>
References: <202310172247.b9959bd4-oliver.sang@intel.com>
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On Tue, Oct 17, 2023 at 11:06:42PM +0800, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed a -99.8% regression of stress-ng.splice.ops_per_sec on:
> 
> 
> commit: 1b057bd800c3ea0c926191d7950cd2365eddc9bb ("drivers/char/mem: implement splice() for /dev/zero, /dev/full")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> 
> testcase: stress-ng
> test machine: 64 threads 2 sockets Intel(R) Xeon(R) Gold 6346 CPU @ 3.10GHz (Ice Lake) with 256G memory
> parameters:
> 
> 	nr_threads: 100%
> 	testtime: 60s
> 	class: pipe
> 	test: splice
> 	cpufreq_governor: performance
> 
> 
> In addition to that, the commit also has significant impact on the following tests:
> 
> +------------------+-------------------------------------------------------------------------------------------------+
> | testcase: change | stress-ng: stress-ng.splice.ops_per_sec 38.9% improvement                                       |

So everything now goes faster, right?  -99.8% regression means 99.8%
faster?

thanks,

greg k-h