From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751454AbeEDM7i (ORCPT ); Fri, 4 May 2018 08:59:38 -0400 Received: from 9pmail.ess.barracuda.com ([64.235.154.211]:56216 "EHLO 9pmail.ess.barracuda.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751172AbeEDM7g (ORCPT ); Fri, 4 May 2018 08:59:36 -0400 Subject: Re: [RFC PATCH] MIPS: Oprofile: Drop support To: Robert Richter CC: James Hogan , Ralf Baechle , , Huacai Chen , , Jiaxun Yang , Krzysztof Kozlowski , References: <1524574554-7451-1-git-send-email-matt.redfearn@mips.com> <20180424130511.GB28813@saruman> <5e464a40-4e4d-dde4-b5b5-ceb637dc5f38@mips.com> <20180504093002.GC4493@rric.localdomain> <20180504102600.GD4493@rric.localdomain> <294858af-9164-f0c3-62d3-d6b643e89e09@mips.com> <20180504122750.GE4493@rric.localdomain> From: Matt Redfearn Message-ID: <4b4943e5-bc87-3981-1d6c-28171e56c907@mips.com> Date: Fri, 4 May 2018 13:59:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180504122750.GE4493@rric.localdomain> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.155.41] X-ClientProxiedBy: mipsdag02.mipstec.com (10.20.40.47) To mipsdag02.mipstec.com (10.20.40.47) X-BESS-ID: 1525438751-531715-9753-78178-1 X-BESS-VER: 2018.5-r1804261738 X-BESS-Apparent-Source-IP: 12.201.5.32 X-BESS-Outbound-Spam-Score: 0.00 X-BESS-Outbound-Spam-Report: Code version 3.2, rules version 3.2.2.192689 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------- 0.00 BSF_BESS_OUTBOUND META: BESS Outbound X-BESS-Outbound-Spam-Status: SCORE=0.00 using account:ESS59374 scores of KILL_LEVEL=7.0 tests=BSF_BESS_OUTBOUND X-BESS-BRTS-Status: 1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Robert, On 04/05/18 13:27, Robert Richter wrote: > On 04.05.18 12:03:12, Matt Redfearn wrote: >>> As said, oprofile version 0.9.x is still available for cpus that do >>> not support perf. What is the breakage? >> >> The breakage I originally set out to fix was the MT support in perf. >> https://www.linux-mips.org/archives/linux-mips/2018-04/msg00259.html >> >> Since the perf code shares so much copied code from oprofile, those same >> issues exist in oprofile and ought to be addressed. But as newer oprofile >> userspace does not use the (MIPS) kernel oprofile code, then we could, >> perhaps, just remove it (as per the RFC). That would break legacy tools >> (0.9.x) though... > > Those support perf: > > (CPU_MIPS32 || CPU_MIPS64 || CPU_R10000 || CPU_SB1 || CPU_CAVIUM_OCTEON || CPU_XLP || CPU_LOONGSON3) > > Here is the total list of CPU_*: > > $ git grep -h config.CPU_ arch/mips/ | sort -u | wc -l > 79 To be fair, that list for oprofile is not much different: arch/mips/oprofile/Makefile: oprofile-$(CONFIG_CPU_MIPS32) += op_model_mipsxx.o oprofile-$(CONFIG_CPU_MIPS64) += op_model_mipsxx.o oprofile-$(CONFIG_CPU_R10000) += op_model_mipsxx.o oprofile-$(CONFIG_CPU_SB1) += op_model_mipsxx.o oprofile-$(CONFIG_CPU_XLR) += op_model_mipsxx.o oprofile-$(CONFIG_CPU_LOONGSON2) += op_model_loongson2.o oprofile-$(CONFIG_CPU_LOONGSON3) += op_model_loongson3.o However, since those are generally CPU families rather than individual CPUs, the number of models supported by each framework tells a different story: git grep -h ops.cpu_type arch/mips/oprofile | wc -l 20 git grep -h pmu.name arch/mips/kernel/perf_event* | wc -l 17 The difference is mainly older CPUs - M14Kc, 20K, loongson1, etc. But yes you are right dropping it would kill profiling for them - that being the case I guess oprofile should remain and instead just remove support for the MT capable CPUs (34K, interAptiv) which are all supported by perf. Thanks, Matt > > The comparisation might not be accurate, but at least gives a hint > that there are many cpus not supporting perf. You would drop profiling > support at al to them. > > If it is too hard to also fix the oprofile code (code duplication > seems the main issue here), then it would be also ok to blacklist > newer cpus to enable oprofile kernel code (where it is broken). > > -Robert >