| From | Andy Lutomirski <> | Subject | [PATCH v2 31/36] x86/entry: Force inlining of 32-bit syscall code | Date | Mon, 5 Oct 2015 17:48:19 -0700 |
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On systems that support fast syscalls, we only really care about the performance of the fast syscall path. Forcibly inline it and add a likely annotation.
This saves 4-6 cycles.
Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/entry/common.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 1d95f8835322..6e1ea6a401f2 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -324,9 +324,11 @@ __visible void syscall_return_slowpath(struct pt_regs *regs) #if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) /* * Does a 32-bit syscall. Called with IRQs on and does all entry and - * exit work and returns with IRQs off. + * exit work and returns with IRQs off. This function is extremely hot + * in workloads that use it, and it's usually called from + * do_fast_syscall_32, so forcibly inline it to improve performance. */ -static void do_syscall_32_irqs_on(struct pt_regs *regs) +static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) { struct thread_info *ti = pt_regs_to_thread_info(regs); unsigned int nr = (unsigned int)regs->orig_ax; @@ -345,7 +347,7 @@ static void do_syscall_32_irqs_on(struct pt_regs *regs) nr = syscall_trace_enter(regs); } - if (nr < IA32_NR_syscalls) { + if (likely(nr < IA32_NR_syscalls)) { /* * It's possible that a 32-bit syscall implementation * takes a 64-bit parameter but nonetheless assumes that -- 2.4.3
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