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From:   "Huang\, Ying" <ying.huang@intel.com>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     kernel test robot <xiaolong.ye@intel.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        LKP <lkp@01.org>, Aaron Lu <aaron.lu@intel.com>
Subject: Re: [lkp-robot] [Kbuild] 050e9baa9d: netperf.Throughput_total_tps -5.6% regression (FYI)
References: <20180621080624.GO11011@yexl-desktop>
        <CA+55aFxXCD8qLfHcnshLR2_Feb=RLkOFfCeqPF_sShy7rK2cAw@mail.gmail.com>
Date:   Thu, 21 Jun 2018 16:25:53 +0800
In-Reply-To: <CA+55aFxXCD8qLfHcnshLR2_Feb=RLkOFfCeqPF_sShy7rK2cAw@mail.gmail.com>
        (Linus Torvalds's message of "Thu, 21 Jun 2018 17:15:09 +0900")
Message-ID: <87muvoh7fy.fsf@yhuang-dev.intel.com>
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Hi, Linus,

Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Thu, Jun 21, 2018 at 5:10 PM kernel test robot <xiaolong.ye@intel.com> wrote:
>>
>> FYI, we noticed a -5.6% regression of netperf.Throughput_total_tps
>> due to commit 050e9b ("Kbuild: rename CC_STACKPROTECTOR[_STRONG]
>> config variables")
>
> That's perhaps a surprisingly large cost to stack protector, but you
> did move from "no stack protector at all":
>
>> $ grep STACKPROTECTOR config-4.17.0-11782-gbe779f0
>> CONFIG_HAVE_CC_STACKPROTECTOR=y
>> CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
>> # CONFIG_CC_STACKPROTECTOR is not set
>> CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
>
> To having the *strong* stack protector enabled:
>
>> $ grep STACKPROTECTOR config-4.17.0-11783-g050e9baa
>> CONFIG_HAVE_CC_STACKPROTECTOR=y
>> CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
>> CONFIG_STACKPROTECTOR=y
>> CONFIG_STACKPROTECTOR_STRONG=y
>> CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
>
> so you're testing the "no overhead" case to the "worst overhead" case.

Do you have interest in some other comparison?

Best Regards,
Huang, Ying