On Mon, Aug 15, 2022 at 9:25 AM Owen Rafferty <owen@xxxxxxxxxxxxxxxx> wrote:
>
> On 22/08/14 09:23AM, Masahiro Yamada wrote:
> > On Fri, Aug 12, 2022 at 11:36 PM Owen Rafferty <owen@xxxxxxxxxxxxxxxx> wrote:
> > >
> > > Remove the bash build dependency for those who otherwise do not
> > > have it installed. This also provides a significant speedup:
> > >
> > > $ make defconfig
> > > $ make yes2modconfig
> > >
> > > ...
> > >
> > > $ find . -name "*.o" | grep -v vmlinux | wc
> > > 3169 3169 89615
> > > $ export NM=nm
> > > $ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1
> > > ./scripts/check-local-export'
> > >
> > > Without patch:
> > > 0m15.90s real 0m12.17s user 0m05.28s system
> > >
> > > With patch:
> > > dash + nawk
> > > 0m02.16s real 0m02.92s user 0m00.34s system
> > >
> > > dash + busybox awk
> > > 0m02.36s real 0m03.36s user 0m00.34s system
> > >
> > > dash + gawk
> > > 0m02.07s real 0m03.26s user 0m00.32s system
> > >
> > > bash + gawk
> > > 0m03.55s real 0m05.00s user 0m00.54s system
> > >
> > > Signed-off-by: Owen Rafferty <owen@xxxxxxxxxxxxxxxx>
> >
> >
> >
> >
> > How did you get those small numbers?
> >
> >
> > The script invokes ${NM} internally,
> > so it is impossible to become faster than nm.
> >
> > For me, it takes 55 sec just for running nm.
> >
> >
> >
> >
> > $ find . -name "*.o" | wc
> > 3191 3191 90085
> >
> > $ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1 nm >/dev/null'
> > nm: ./arch/x86/entry/vdso/vdso32/note.o: no symbols
> > nm: ./arch/x86/entry/vdso/vdso-note.o: no symbols
> >
> > real 0m55.783s
> > user 0m24.887s
> > sys 0m30.905s
> >
>
> I'm not exactly sure. I get compatible numbers with just nm.
>
> $ find . -name "*.o" | grep -v vmlinux | wc
> 3169 3169 89615
>
> $ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1 nm'
> 0m02.02s real 0m01.77s user 0m00.43s system
>
About the slowness of nm, it might depend on the GNU binutils version.
I tried some versions in docker.
On Ubuntu 18.04:
$ nm -V | head -n1
GNU nm (GNU Binutils for Ubuntu) 2.30
$ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1 nm >/dev/null'
nm: ./arch/x86/entry/vdso/vdso-note.o: no symbols
nm: ./arch/x86/entry/vdso/vdso32/note.o: no symbols
real 0m2.694s
user 0m2.201s
sys 0m0.729s
On Ubuntu 20.04:
$ nm -V | head -n1
GNU nm (GNU Binutils for Ubuntu) 2.34
$ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1 nm >/dev/null'
nm: ./arch/x86/entry/vdso/vdso-note.o: no symbols
nm: ./arch/x86/entry/vdso/vdso32/note.o: no symbols
real 0m5.287s
user 0m3.356s
sys 0m2.035s
On Ubuntu 22.04:
$ nm -V | head -n1
GNU nm (GNU Binutils for Ubuntu) 2.38
$ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1 nm >/dev/null'
nm: ./arch/x86/entry/vdso/vdso-note.o: no symbols
nm: ./arch/x86/entry/vdso/vdso32/note.o: no symbols
real 0m37.107s
user 0m14.121s
sys 0m23.229s
So, 'nm' is progressively becoming slower and slower.
With the recent nm, most of the time for running check-local-export
is consumed for 'nm'.
llvm-nm is a little faster, but it is still slow.
--
Best Regards
Masahiro Yamada
