On Tue, Feb 14, 2017 at 12:11 AM, Kyle Huey <[email protected]> wrote: > GCC generates lousy code in __switch_to_xtra. This patch series is an > updated version of tglx's patches from last year > (https://lkml.org/lkml/2016/12/15/432) that address review comments. > > Since v1: > Part 1 - x86/process: Optimize TIF checks in __switch_to_xtra() > - READ_ONCE annotations added as requested by Andy Lutomirski > > Part 2 - x86/process: Correct and optimize TIF_BLOCKSTEP switch > - DEBUGCTLMSR_BTF is now modified when either the previous or > next or both tasks use it, because the MSR is "highly magical". > > Part 3 - x86/process: Optimize TIF_NOTSC switch > - Unchanged > > I didn't introduce a cpufeature for blockstep because that would > add additional overhead compared to the existing code, where it's > generally known at compile time that blockstep is supported. Perhaps > we should just BUG_ON(!arch_has_block_step()) here if we really > care to check anything. > > arch/x86/include/asm/msr-index.h | 1 + > arch/x86/include/asm/tlbflush.h | 10 ++++++++++ > arch/x86/kernel/process.c | 76 > +++++++++++++++++++++++++++++++++++----------------------------------------- > 3 files changed, 46 insertions(+), 41 deletions(-) >
Has anyone had a change to look at these? - Kyle
