Date: Wed, 12 Jun 2013 21:43:14 -0400 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: Thinking about release On Thu, Jun 13, 2013 at 01:33:16PM +1200, Andre Renaud wrote: > Hi Rich, > > > Most of the other major items left on the agenda since the last > > release are probably not going to happen right away unless there's a > > volunteer to do them (zoneinfo, cpuset/affinity, string functions > > cleanup, C++ ABI matching, ARM-optimized memcpy) and one, the ld.so > > symlink direction issue, still requires some serious discussion and > > decision-making. > > Regarding the ARM-optimisations - I am happy to have a go at providing > a cleaned up implementation, although I can't recall what the final > consensus was on how this should be implemented. A simple ARMv4 I think the first step should be benchmarking on real machines. Somebody tried the asm that was posted and claimed it was no faster than musl's C code; I don't know the specific hardware they were using and I don't even recall right off who made the claim or where it was reported, but I think before we start writing or importing code we need to have a good idea how the current C code compares in performance to other "optimized" implementations. > implementation would cover all the bases, providing near universal > support, although would obviously not support the more modern > platforms. Is there any intention to move the base level support up to > ARMv5? I would consider that reasonable, given the age of ARMv4. > Alternatively, should we have multiple implementations > (ARMv4/ARMv5/ARMv7), and choose between them either at compile or > run-time? It's possible to branch based on __hwcap at runtime, if this would really help. > Obviously this stuff is probably not destined for the immediate > release, but more likely for the one after that. Yes, this looks like it will be a process that takes some time to sort out the facts and then tune the code. For what it's worth, I just did my first runs of libc-bench on real ARM hardware (well, an FPGA-based ARM). memset is half the speed of glibc's, but strchr and strlen are about 40% faster than glibc's. I don't think libc-bench is really a good benchmark as of yet, so we should probably develop more detailed tests. Rich
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