Hi Will, Thanks for the reply.
Will Newton <will.new...@linaro.org> writes: > On 27 August 2013 04:16, Michael Hudson-Doyle <michael.hud...@linaro.org> > wrote: > > Hi Michael, > >> There has been interest from LEG members to ensure that optimal library >> routines are used on their platforms. My understanding is that the >> "correct" way of doing this these days is to use ifuncs to select the >> best implementation for a given system. >> >> I see that glibc 2.18 contains an ifunc-ed version of memcpy. Does the >> TCWG have a hit list of other functions that might get the same >> treatment? If so, does it have a plan and the resources to implement >> them? If it's a matter of resources, I think LEG might be able to help >> there. > > I am not aware of any immediate plans for adding new functions, but we > have a few JIRA cards open to write better implementations of various > string functions. memset in particular looks like it should be fairly > easy to optimise further with NEON. OK. The main libc functions I've seen showing up in perf reports have been memcpy and malloc/free so I think you're on target there... > We have tests and benchmarks for string functions in the > cortex-strings package on launchpad and development of new code has > been done there under a liberal license before pushing to > glibc/newlib/bionic/etc. Right. But as far as you know offhand there's nothing in the pipeline that is likely to have different optimal implementations on A8/A9/A15? > There's been some investigation into optimising libm too, but I think > any work on that would likely be further away still. OK. > Note that ifunc resolvers get passed the HWCAP bits from the kernel, > so that is the granularity of decision that can simply be resolved - > that essentially means you can dispatch based on the presence of NEON > or VFP rather than say any micro-architectural details (although you > could in theory extract this information in the resolver if it is > easily accessible in userspace). Oh hm. So you can't easily separate A8/A9/A15 per se? That's potentially unfortunate from what I hear, but is quite a way away from my area of expertise :-) Cheers, mwh _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
