From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (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 3wLkRg1Sy7zDqFW for ; Mon, 8 May 2017 10:49:50 +1000 (AEST) Subject: Re: [PATCH v6 2/7] perf/x86/intel: Record branch type From: "Jin, Yao" To: Jiri Olsa Cc: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com, linuxppc-dev@lists.ozlabs.org References: <1492690075-17243-1-git-send-email-yao.jin@linux.intel.com> <1492690075-17243-3-git-send-email-yao.jin@linux.intel.com> <20170423135559.GA23073@krava> Message-ID: Date: Mon, 8 May 2017 08:49:44 +0800 MIME-Version: 1.0 In-Reply-To: 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 4/24/2017 8:47 AM, Jin, Yao wrote: > > > On 4/23/2017 9:55 PM, Jiri Olsa wrote: >> On Thu, Apr 20, 2017 at 08:07:50PM +0800, Jin Yao wrote: >> >> SNIP >> >>> +#define X86_BR_TYPE_MAP_MAX 16 >>> + >>> +static int >>> +common_branch_type(int type) >>> +{ >>> + int i, mask; >>> + const int branch_map[X86_BR_TYPE_MAP_MAX] = { >>> + PERF_BR_CALL, /* X86_BR_CALL */ >>> + PERF_BR_RET, /* X86_BR_RET */ >>> + PERF_BR_SYSCALL, /* X86_BR_SYSCALL */ >>> + PERF_BR_SYSRET, /* X86_BR_SYSRET */ >>> + PERF_BR_INT, /* X86_BR_INT */ >>> + PERF_BR_IRET, /* X86_BR_IRET */ >>> + PERF_BR_JCC, /* X86_BR_JCC */ >>> + PERF_BR_JMP, /* X86_BR_JMP */ >>> + PERF_BR_IRQ, /* X86_BR_IRQ */ >>> + PERF_BR_IND_CALL, /* X86_BR_IND_CALL */ >>> + PERF_BR_NONE, /* X86_BR_ABORT */ >>> + PERF_BR_NONE, /* X86_BR_IN_TX */ >>> + PERF_BR_NONE, /* X86_BR_NO_TX */ >>> + PERF_BR_CALL, /* X86_BR_ZERO_CALL */ >>> + PERF_BR_NONE, /* X86_BR_CALL_STACK */ >>> + PERF_BR_IND_JMP, /* X86_BR_IND_JMP */ >>> + }; >>> + >>> + type >>= 2; /* skip X86_BR_USER and X86_BR_KERNEL */ >>> + mask = ~(~0 << 1); >> is that a fancy way to get 1 into the mask? what do I miss? >> >>> + >>> + for (i = 0; i < X86_BR_TYPE_MAP_MAX; i++) { >>> + if (type & mask) >>> + return branch_map[i]; >> I wonder some bit search would be faster in here, but maybe not big deal >> >> jirka > > I just think the branch_map[] doesn't contain many entries (16 entries > here), so maybe checking 1 bit one time should be acceptable. I just > want to keep the code simple. > > But if the number of entries is more (e.g. 64), maybe it'd better > check 2 or 4 bits one time. > > Thanks > Jin Yao > Hi, Is this explanation OK? Since for tools part, it's Acked-by: Jiri Olsa. I just want to know if the kernel part is OK either? Thanks Jin Yao