[PATCH 0/6] powerpc: SMT priority (PPR) save and restore On P7 systems, users can define SMT priority levels 2,3 and 4 for processes so that some can run higher priority than the other ones. In the current kernel, the default priority is set to 4 which prohibits processes for using higher priority. Also the kernel boosts the priority to 4 during exceptions without saving the user defined priorities when the task enters the kernel. So we will be loosing the process PPR value and can not be restored it back when the task exits the kernel.
This patchset implements saving and restore the user defined PPR value for all tasks. With null_syscall testcase (http://ozlabs.org/~anton/junkcode/null_syscall.c), this feature takes around extra 10 CPU cycles on average for 25 samples. Haren Myneni (6): powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to caller powerpc: Define CPU_FTR_HAS_PPR powerpc: Increase exceptions arrays in paca struct to save PPR powerpc: Define ppr in thread_struct powerpc: Macros for saving/restore PPR powerpc: Implement PPR save/restore arch/powerpc/include/asm/cputable.h | 6 ++- arch/powerpc/include/asm/exception-64s.h | 45 ++++++++++++++++++++++++++---- arch/powerpc/include/asm/paca.h | 6 ++-- arch/powerpc/include/asm/ppc_asm.h | 27 ++++++++++++++++- arch/powerpc/include/asm/processor.h | 6 ++++ arch/powerpc/include/asm/reg.h | 1 + arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kernel/entry_64.S | 6 +++- arch/powerpc/kernel/exceptions-64e.S | 3 +- arch/powerpc/kernel/exceptions-64s.S | 15 +++++---- arch/powerpc/kernel/process.c | 2 + 11 files changed, 96 insertions(+), 22 deletions(-) _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
