On 04/12/2025 09:21, Jinjie Ruan wrote: > After switch arm64 to Generic Entry, a new hotspot syscall_exit_work() > appeared because syscall_exit_work() is no longer inlined. so inline
Before this series the call to syscall_trace_exit() in el0_svc_common() could not be inlined, so "no longer inlined" doesn't seem to be accurate. > syscall_exit_work(), and it has 2.6% performance uplift on perf bench > basic syscall on kunpeng920 as below. That seems strange. syscall_exit_work() is only called if some flag in SYSCALL_WORK_EXIT is set, which means that we're doing something special like tracing. That shouldn't be the case when running a simple perf bench syscall. Also worth nothing that its counterpart (syscall_trace_enter())) is not currently inlined, the asymmetry would have to be justified. > | Metric | W/O this patch | With this patch | Change | > | ---------- | -------------- | --------------- | --------- | > | Total time | 2.171 [sec] | 2.114 [sec] | ↓2.6% | > | usecs/op | 0.217192 | 0.211453 | ↓2.6% | > | ops/sec | 4,604,225 | 4,729,178 | ↑2.7% | > > Signed-off-by: Jinjie Ruan <[email protected]> > --- > include/linux/entry-common.h | 63 ++++++++++++++++++++++++++++++++++- > kernel/entry/syscall-common.c | 59 ++------------------------------ These changes are purely generic, surely all architectures using GENERIC_ENTRY should get similar benefits (assuming LTO isn't used)? > 2 files changed, 64 insertions(+), 58 deletions(-) > > diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h > index cd6dacb2d8bf..2f84377fb016 100644 > --- a/include/linux/entry-common.h > +++ b/include/linux/entry-common.h > @@ -2,6 +2,7 @@ > #ifndef __LINUX_ENTRYCOMMON_H > #define __LINUX_ENTRYCOMMON_H > > +#include <linux/audit.h> > #include <linux/irq-entry-common.h> > #include <linux/ptrace.h> > #include <linux/seccomp.h> > @@ -128,6 +129,41 @@ static __always_inline long > syscall_enter_from_user_mode(struct pt_regs *regs, l > return ret; > } > > +/* > + * If SYSCALL_EMU is set, then the only reason to report is when > + * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall > + * instruction has been already reported in syscall_enter_from_user_mode(). > + */ > +static __always_inline bool report_single_step(unsigned long work) > +{ > + if (work & SYSCALL_WORK_SYSCALL_EMU) > + return false; > + > + return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP; > +} > + > +/** > + * arch_ptrace_report_syscall_exit - Architecture specific > + * ptrace_report_syscall_exit. > + * > + * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit(). > + * > + * The main purpose is to support arch-specific ptrace_report_syscall_exit > + * implementation. > + */ > +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs > *regs, > + int step); > + > +#ifndef arch_ptrace_report_syscall_exit > +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs > *regs, > + int step) > +{ > + ptrace_report_syscall_exit(regs, step); > +} > +#endif If we want syscall_exit_work() to be inline, then why would we define this hook in syscall-common.c in patch 12? Might as well define both hooks in entry-common.h right away and avoid some noise here. - Kevin > [...]
