From b6254ced4da6cf28d49fbffe24ee4b3286dcb3f4 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Tue, 18 Aug 2020 17:19:17 +0000 Subject: powerpc/signal: Don't manage floating point regs when no FPU There is no point in copying floating point regs when there is no FPU and MATH_EMULATION is not selected. Create a new CONFIG_PPC_FPU_REGS bool that is selected by CONFIG_MATH_EMULATION and CONFIG_PPC_FPU, and use it to opt out everything related to fp_state in thread_struct. The asm const used only by fpu.S are opted out with CONFIG_PPC_FPU as fpu.S build is conditionnal to CONFIG_PPC_FPU. The following app spends approx 8.1 seconds system time on an 8xx without the patch, and 7.0 seconds with the patch (13.5% reduction). On an 832x, it spends approx 2.6 seconds system time without the patch and 2.1 seconds with the patch (19% reduction). void sigusr1(int sig) { } int main(int argc, char **argv) { int i = 100000; signal(SIGUSR1, sigusr1); for (;i--;) raise(SIGUSR1); exit(0); } Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/7569070083e6cd5b279bb5023da601aba3c06f3c.1597770847.git.christophe.leroy@csgroup.eu --- arch/powerpc/include/asm/processor.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/powerpc/include/asm/processor.h') diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 333e3b6c76fb..0792530bedef 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -164,8 +164,10 @@ struct thread_struct { #endif /* Debug Registers */ struct debug_reg debug; +#ifdef CONFIG_PPC_FPU_REGS struct thread_fp_state fp_state; struct thread_fp_state *fp_save_area; +#endif int fpexc_mode; /* floating-point exception mode */ unsigned int align_ctl; /* alignment handling control */ #ifdef CONFIG_HAVE_HW_BREAKPOINT -- cgit v1.2.3