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SubjectRe: [PATCH 2/4] trace: avoid calling cc-option -mrecord-mcount for every Makefile
On Mon, Aug 06, 2018 at 11:07:40AM -0700, Andi Kleen wrote:
> On Mon, Aug 06, 2018 at 03:17:44PM +0200, Vasily Gorbik wrote:
> > Currently if CONFIG_FTRACE_MCOUNT_RECORD is enabled -mrecord-mcount
> > compiler flag support is tested for every Makefile.
> Good catch. Does it make a measurable compile time difference?

A bit more than couple of seconds, but it does make a difference for a
delta build:
with patch:
real 0m9.405s
user 0m6.966s
sys 0m2.287s

real 0m12.153s
user 0m9.058s
sys 0m3.026s

with -j48 on s390 24 cores lpar:
with patch:
real 0m1.949s
user 0m7.034s
sys 0m2.400s

real 0m2.255s
user 0m9.243s
sys 0m3.266s

> >
> > Top 4 cc-option usages:
> > 511 -mrecord-mcount

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