On 16.01.25 г. 8:51 ч., Ethan Zhao wrote:
External interrupts (EVENT_TYPE_EXTINT) and system calls (EVENT_TYPE_OTHER) occur more frequently than other events in a typical system. Prioritizing these events saves CPU cycles and optimizes the efficiency of performance- critical paths.
<snip>
Can you also include some performance numbers?
Signed-off-by: Ethan Zhao haifeng.zhao@linux.intel.com
base commit: 619f0b6fad524f08d493a98d55bac9ab8895e3a6
arch/x86/entry/entry_fred.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/arch/x86/entry/entry_fred.c b/arch/x86/entry/entry_fred.c index f004a4dc74c2..591f47771ecf 100644 --- a/arch/x86/entry/entry_fred.c +++ b/arch/x86/entry/entry_fred.c @@ -228,9 +228,18 @@ __visible noinstr void fred_entry_from_user(struct pt_regs *regs) /* Invalidate orig_ax so that syscall_get_nr() works correctly */ regs->orig_ax = -1;
- switch (regs->fred_ss.type) {
- case EVENT_TYPE_EXTINT:
- if (regs->fred_ss.type == EVENT_TYPE_EXTINT) return fred_extint(regs);
- else if (regs->fred_ss.type == EVENT_TYPE_OTHER)
return fred_other(regs);- /*
* Dispatch EVENT_TYPE_EXTINT and EVENT_TYPE_OTHER(syscall) type events* first due to their high probability and let the compiler create binary search* dispatching for the remaining events*/
nit: At least to me it makes sense to have the comment above the 'if' so that the flow is linear.
- switch (regs->fred_ss.type) { case EVENT_TYPE_NMI: if (likely(regs->fred_ss.vector == X86_TRAP_NMI)) return fred_exc_nmi(regs);
@@ -245,8 +254,6 @@ __visible noinstr void fred_entry_from_user(struct pt_regs *regs) break; case EVENT_TYPE_SWEXC: return fred_swexc(regs, error_code);
- case EVENT_TYPE_OTHER:
return fred_other(regs);@@ -260,9 +267,15 @@ __visible noinstr void fred_entry_from_kernel(struct pt_regs *regs) /* Invalidate orig_ax so that syscall_get_nr() works correctly */ regs->orig_ax = -1;
- switch (regs->fred_ss.type) {
- case EVENT_TYPE_EXTINT:
- if (regs->fred_ss.type == EVENT_TYPE_EXTINT) return fred_extint(regs);
- /*
* Dispatch EVENT_TYPE_EXTINT type event first due to its high probability* and let the compiler do binary search dispatching for the other events*/- switch (regs->fred_ss.type) { case EVENT_TYPE_NMI: if (likely(regs->fred_ss.vector == X86_TRAP_NMI)) return fred_exc_nmi(regs);