Re: [RFC PATCH v3 7/7] x86/unwind/orc: remove run-time ORC unwind tables sort

Josh Poimboeuf
2019-11-15T17:46:59Z

On Fri, Nov 15, 2019 at 04:51:24PM +0000, David Laight wrote:
> From: Shile Zhang
> > Sent: 15 November 2019 06:48
> ...
> > arch/x86/kernel/unwind_orc.c | 8 +++++---
> > 1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
> > index 332ae6530fa8..280da6fa9922 100644
> > --- a/arch/x86/kernel/unwind_orc.c
> > +++ b/arch/x86/kernel/unwind_orc.c
> > @@ -273,9 +273,11 @@ void __init unwind_init(void)
> > return;
> > }
> >
> > - /* Sort the .orc_unwind and .orc_unwind_ip tables: */
> > - sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp,
> > - orc_sort_swap);
> > + /*
> > + * Note, orc_unwind and orc_unwind_ip tables has been sorted in
> > + * vmlinux link phase by sorttable tool at build time.
> > + * Its ready for binary search now.
> > + */
>
> How fast is sort() if the table is sorted?
> Relying on the kernel sources and build scripts always being in sync seems dangerous.
> Probably better to leave the sort in for a release of two.

This patch comes after the build script changes, so they'd be in sync.
What would the concern be?

--
Josh