Messages in this thread | | | Subject | Re: [PATCH v6 1/7] perf/core: Define the common branch type classification | From | "Jin, Yao" <> | Date | Tue, 11 Jul 2017 11:00:55 +0800 |
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On 7/11/2017 10:28 AM, Michael Ellerman wrote: > "Jin, Yao" <yao.jin@linux.intel.com> writes: > >> On 7/10/2017 9:46 PM, Peter Zijlstra wrote: >>> On Mon, Jul 10, 2017 at 08:10:50AM -0500, Segher Boessenkool wrote: >>> >>>>> PERF_BR_INT is triggered by instruction "int" . >>>>> PERF_BR_IRQ is triggered by interrupts, traps, faults (the ring 0,3 >>>>> transition). >>>> So your "PERF_BR_INT" is a system call? >>> The "INT" thing has indeed been used as system call mechanism (typically >>> INT 80). But these days we have special purpose syscall instructions. >>> >>> It could maybe be compared to the PPC "Unconditional TRAP with >>> immediate" where you use the immediate value as an index into a handler >>> vector. >>> >>>> And PERF_BR_IRQ is not an interrupt request (as its name suggests), >>>> not what we call an "external interrupt" either; instead it is every >>>> interrupt that is not a system call? >>> It is actual interrupts, but also faults, traps and all the other >>> exceptions not caused by "INT" I think. >>> >> Yes. It's interrupt, traps, faults. If from is in the user space and to >> is in the kernel, it indicates the ring3 -> ring0 transition. >> >> If the from instruction is not syscall or other ring transition >> instruction, it should be interrupt, traps and faults. That's how we get >> the PERF_BR_IRQ on x86. >> >> Anyway, maybe we just use a minimum but the most common set of branch >> types now, it could be a good start and acceptable on all architectures. >> >> PERF_BR_COND = 1, /* conditional */ >> PERF_BR_UNCOND = 2, /* unconditional */ >> PERF_BR_IND = 3, /* indirect */ >> PERF_BR_CALL = 4, /* call */ >> PERF_BR_IND_CALL = 5, /* indirect call */ >> PERF_BR_RET = 6, /* return */ > That would be fine by me, if you're sick of talking about it and just > want to get it merged :) :) > > I think you could expand it a bit, this list would cover the vast bulk > of branch types for us: > > PERF_BR_COND /* Conditional */ > PERF_BR_UNCOND /* Unconditional */ > PERF_BR_IND /* Indirect */ > PERF_BR_CALL /* Function call */ > PERF_BR_IND_CALL /* Indirect function call */ > PERF_BR_RET /* Function return */ > PERF_BR_SYSCALL /* Syscall */ > PERF_BR_SYSRET /* Syscall return */ > PERF_BR_COND_CALL /* Conditional function call */ > PERF_BR_COND_RET /* Conditional function return */ > > cheers
OK, accept! Use 4 bits for above branch types and we can reserve 5 for potential future types.
Thanks Jin Yao
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