Hi, On 18 November 2013 21:16, Jan Kratochvil <jan.kratoch...@redhat.com> wrote: > On Mon, 18 Nov 2013 18:49:45 +0100, Jiri Olsa wrote: >> I think it's an option.. but it'll simpler to try the libdw >> interface first and see if it's good/fast enough.. > > The elfutils libdw unwinder is being upstreamed these weeks, the x86* unwinder > itself is already upstream now. Do you know about the support of AARCH64, both in 64-bit and 32-bit (compat) mode? I would be glad to give it a try.
>> also I recall discussing the speed with libdw developer > > My tests with perf using elfutils unwinder were 10x faster than libunwind; > this is by some simple caching of ELF files. Sure a similar cache could be > implemented also for libunwind. But the cache is a wrong solution. > > The problem is that currently perf loads the ELF files again and again for > every process as the ELF file always gets automatically relocated for the > address where it was loaded. The right way is to load the ELF file only once > and access always the same copy with process-specific displacement only. > > I did not investigate how much feasible it is with libunwind. For elfutils > there is pmachata/sharing unfinished branch from 2008 to implement that. > I have not checked it more before the unwinder gets fully upstreamed. > > > Jan Jean > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
