Re: [PATCH v4 19/39] unwind_user/sframe: Add support for reading .sframe contents

[Jens Remus]

On 28.01.2025 01:39, Andrii Nakryiko wrote:
> On Fri, Jan 24, 2025 at 1:41 PM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> > On Fri, Jan 24, 2025 at 10:02:46AM -0800, Andrii Nakryiko wrote:
> > > On Tue, Jan 21, 2025 at 6:32 PM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:

> > > > +       fre_addr = sec->fres_start + fde->fres_off;
> > > > +
> > > > +       for (i = 0; i < fde->fres_num; i++) {
> > >
> > > why not binary search? seem more logical to guard against cases with
> > > lots of FREs and be pretty fast in common case anyways.
> >
> > That would be nice, but the FREs are variable-sized and you don't know
> > how big one is until you start reading it.
>
> ah, another non-obvious thing, yeah... do you think it's worth fixing
> this and making FREs binary searchable in v3?
>
> Indu, do you have some stats on distribution of FRE count per FDE in practice?
>
> Tbh, FRE format is bothering me quite a lot... but let's discuss that
> in another thread with you and Indu

I would be interested to be part of that discussion.  I could share some
preliminary stats from my s390 work.

Thanks and regards,
Jens
--
Jens Remus
Linux on Z Development (D3303)
+49-7031-16-1128 Office
jremus@xxxxxxxxxx

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