On Wed, 2017-07-12 at 21:15 -0700, Andi Kleen wrote: > On Thu, Jul 13, 2017 at 05:03:00AM +0200, Mike Galbraith wrote: > > On Wed, 2017-07-12 at 15:30 -0700, Andi Kleen wrote: > > > Josh Poimboeuf <jpoimboe@xxxxxxxxxx> writes: > > > > > > > > The ORC data format does have a few downsides compared to DWARF. The > > > > ORC unwind tables take up ~1MB more memory than DWARF eh_frame tables. > > > > > > > Can we have an option to just use dwarf instead? For people > > > who don't want to waste a MB+ to solve a problem that doesn't > > > exist (as proven by many years of opensuse kernel experience) > > > > Sure the dwarf unwinder works well for crashes, but at the price of > > demolishing ftrace/perf utility. > > You mean the unwind performance? Yeah, it hurts.. massively, has even been known to kill big boxen. > That's a valid concern, but neither ORC nor dwarf are likely > to address it. However most usages of ftrace/perf shouldn't be that > depending on unwind performance -- just lower the frequency of your > events. > > The only possible win is if the win from not using FP code is > significant enough. On the x86 side the only modern CPUs that should really > care about this are Atoms. Nope, they all care. Measure performance delta of fast/light stuff. Maybe I'm expecting too much good stuff to follow, but don't spoil it for me, I think I'm looking at a real winner :) -Mike -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
