> This getcpu cache is an alternative to the sched_getcpu() vdso which has > a few benefits:
Note the first version of getcpu() I proposed had a cache. But it was rejected. > - It is faster to do a memory read that to call a vDSO, > - This cached value can be read from within an inline assembly, which > makes it a useful building block for restartable sequences. On x86 we already have the de-facto ABI of using LSL with the magic segment directly. While that is a few cycles slower than a memory load I question the difference is big enough to justify a new system call, and risk slow page fault in context switches. BTW the vdso could be also optimized I think. For example glibc today does some stupid (slow) things with it, like doing double iindirect jumps. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
