Re: performance: memcpy vs. __copy_tofrom_user
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2008-10-13 20:50:27
It doesn't need to be done in non-preemptible sections, if you have a separate per-thread save area for kernel fp/altivec use (and appropriate flags so an FP unavailable handler knows which regs to restore), and you can avoid using it in a preempting context.
Yuck. Ben.