Re: [lkp-robot] [Kbuild] 050e9baa9d: netperf.Throughput_total_tps -5.6% regression (FYI)

[Linus Torvalds]

On Thu, Jun 21, 2018 at 5:10 PM kernel test robot <xiaolong.ye@xxxxxxxxx> 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.

                Linus