Frederic Weisbecker <fweis...@gmail.com> writes: > 2013/2/15 Kevin Hilman <khil...@linaro.org>: >> Frederic Weisbecker <fweis...@gmail.com> writes: >> >>> Ingo, >>> >>> Please pull the new full dynticks cputime accounting code that >>> can be found at: >>> >>> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git >>> tags/full-dynticks-cputime-for-mingo >>> >>> My last concern is the dependency on CONFIG_64BIT. We rely on cputime_t >>> being u64 for reasonable nanosec granularity implementation. And therefore >>> we need a single instruction fetch to read kernel cpustat for atomicity >>> requirement against concurrent incrementation, which only 64 bit archs >>> can provide. >> >> Actually, moderately recent 32-bit ARMs can do atomic 64-bit load/stores >> too. > > Does gcc automatically handle 64 bit store/loads in one way or does > that require specific CPU instructions?
For atomic load/stores, it requires specific instructions that gcc will not generate, so the atomic64 accessors are needed on ARM. Kevin -- 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/
