From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3x66KV2tYyzDq60 for ; Tue, 11 Jul 2017 13:01:01 +1000 (AEST) Subject: Re: [PATCH v6 1/7] perf/core: Define the common branch type classification To: Michael Ellerman , Peter Zijlstra , Segher Boessenkool Cc: acme@kernel.org, jolsa@kernel.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, kan.liang@intel.com, ak@linux.intel.com, linuxppc-dev@lists.ozlabs.org, Linux-kernel@vger.kernel.org, yao.jin@intel.com References: <1492690075-17243-1-git-send-email-yao.jin@linux.intel.com> <1492690075-17243-2-git-send-email-yao.jin@linux.intel.com> <87r2xoj08g.fsf@concordia.ellerman.id.au> <820424b8-d7b3-56cc-2b97-ec570d44ec25@linux.intel.com> <87h8ykvayi.fsf@concordia.ellerman.id.au> <20170710131049.GA13471@gate.crashing.org> <20170710134658.k44bpa7tra2woyiu@hirez.programming.kicks-ass.net> <87shi37lmp.fsf@concordia.ellerman.id.au> From: "Jin, Yao" Message-ID: Date: Tue, 11 Jul 2017 11:00:55 +0800 MIME-Version: 1.0 In-Reply-To: <87shi37lmp.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 7/11/2017 10:28 AM, Michael Ellerman wrote: > "Jin, Yao" 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