From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 8988F7D048 for ; Wed, 6 Jun 2018 03:52:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768AbeFFDwJ (ORCPT ); Tue, 5 Jun 2018 23:52:09 -0400 Received: from exmail.andestech.com ([59.124.169.137]:63771 "EHLO ATCSQR.andestech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752762AbeFFDwI (ORCPT ); Tue, 5 Jun 2018 23:52:08 -0400 X-Greylist: delayed 2049 seconds by postgrey-1.27 at vger.kernel.org; Tue, 05 Jun 2018 23:52:08 EDT Received: from ATCSQR.andestech.com (localhost [127.0.0.2] (may be forged)) by ATCSQR.andestech.com with ESMTP id w563InUH096888 for ; Wed, 6 Jun 2018 11:18:49 +0800 (GMT-8) (envelope-from alankao@andestech.com) Received: from mail.andestech.com (atcpcs16.andestech.com [10.0.1.222]) by ATCSQR.andestech.com with ESMTP id w563Hl2u096787; Wed, 6 Jun 2018 11:17:47 +0800 (GMT-8) (envelope-from alankao@andestech.com) Received: from andestech.com (10.0.1.85) by ATCPCS16.andestech.com (10.0.1.222) with Microsoft SMTP Server id 14.3.123.3; Wed, 6 Jun 2018 11:16:55 +0800 Date: Wed, 6 Jun 2018 11:16:56 +0800 From: Alan Kao To: Palmer Dabbelt CC: , , , , , , , , , , , , , , Subject: Re: [PATCH v5 0/2] perf: riscv: Preliminary Perf Event Support on RISC-V Message-ID: <20180606031655.GB31803@andestech.com> References: <20180425031936.GA7303@andestech.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Originating-IP: [10.0.1.85] X-DNSRBL: X-MAIL: ATCSQR.andestech.com w563Hl2u096787 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Apr 25, 2018 at 09:39:04AM -0700, Palmer Dabbelt wrote: > On Tue, 24 Apr 2018 20:19:36 PDT (-0700), alankao@andestech.com wrote: > >Hi Atish, Palmer, > > > >On Tue, Apr 24, 2018 at 06:15:49PM -0700, Atish Patra wrote: > >>On 4/24/18 5:29 PM, Palmer Dabbelt wrote: > >>>On Tue, 24 Apr 2018 15:16:16 PDT (-0700), atish.patra@wdc.com wrote: > >>>>On 4/24/18 12:44 PM, Palmer Dabbelt wrote: > >>>>>On Tue, 24 Apr 2018 12:27:26 PDT (-0700), atish.patra@wdc.com wrote: > >>>>>>On 4/24/18 11:07 AM, Atish Patra wrote: > >>>>>>>On 4/19/18 4:28 PM, Alan Kao wrote: > >>>>>>>However, I got an rcu-stall for the test "47: Event times". > >>>>>>># ./perf test -v 47 > >>>>>>Got it working. The test tries to attach the event to CPU0 which doesn't > >>>>>>exist in HighFive Unleashed. Changing it to cpu1 works. > >>>>>> > >>>>>>diff --git a/tools/perf/tests/event-times.c b/tools/perf/tests/event-times.c > >>>>>>index 1a2686f..eb11632f 100644 > >>>>>>--- a/tools/perf/tests/event-times.c > >>>>>>+++ b/tools/perf/tests/event-times.c > >>>>>>@@ -113,9 +113,9 @@ static int attach__cpu_disabled(struct perf_evlist > >>>>>>*evlist) > >>>>>> struct cpu_map *cpus; > >>>>>> int err; > >>>>>> > >>>>>>- pr_debug("attaching to CPU 0 as enabled\n"); > >>>>>>+ pr_debug("attaching to CPU 1 as disabled\n"); > >>>>>> > >>>>>>- cpus = cpu_map__new("0"); > >>>>>>+ cpus = cpu_map__new("1"); > >>>>>> if (cpus == NULL) { > >>>>>> pr_debug("failed to call cpu_map__new\n"); > >>>>>> return -1; > >>>>>>@@ -142,9 +142,9 @@ static int attach__cpu_enabled(struct perf_evlist > >>>>>>*evlist) > >>>>>> struct cpu_map *cpus; > >>>>>> int err; > >>>>>> > >>>>>>- pr_debug("attaching to CPU 0 as enabled\n"); > >>>>>>+ pr_debug("attaching to CPU 1 as enabled\n"); > >>>>>> > >>>>>>- cpus = cpu_map__new("0"); > >>>>>>+ cpus = cpu_map__new("1"); > >>>>>> if (cpus == NULL) { > >>>>>> pr_debug("failed to call cpu_map__new\n"); > >>>>>> return -1; > >>>>>> > >>>>>> > >>>>>>Palmer, > >>>>>>Would it be better to officially document it somewhere that CPU0 doesn't > >>>>>>exist in the HighFive Unleashed board ? > >>>>>>I fear that there will be other standard tests/code path that may fail > >>>>>>because of inherent assumption of cpu0 presence. > >>>>> > >>>>>I think the best way to fix this is to just have BBL (or whatever the > >>>>>bootloader is) renumber the CPUs so they're contiguous and begin with 0. > >>>> > >>>>Do you mean BBL will update the device tree that kernel eventually parse > >>>>and set the hart id? > >>>>Sounds good to me unless it acts as a big hack in future boot loaders. > >>> > >>>Right now the machine-mode and supervisor-mode hart IDs are logically separate: > >>>the bootloader just provides the hart ID as a register argument when starting > >>>the kernel. > >> > >>Yes. > >> > >> BBL already needs to enumerate the harts by looking through the > >>>device tree for various other reasons (at least to mask off the harts that > >>>Linux doesn't support), so it's not that much effort to just maintain a mapping > >>>from supervisor-mode hart IDs to machine-mode hart IDs. > >>> > >> > >>But Linux also parses the device tree to get hart ID in > >>riscv_of_processor_hart(). This is used to setup the possible/present cpu > >>map in setup_smp(). > >> > >>Thus, Linux also need to see a device tree with cpu0-3 instead of cpu1-4. > >>Otherwise, present cpu map will be incorrect. Isn't it ? > >> > >>>I have some patches floating around that do this, but appear to do it > >>>incorrectly enough that nothing boots so maybe I'm missing something that makes > >>>this complicated :). > >>> > >> > >>Just a wild guess: May be the because of the above reason ;) > >> > > > >Thanks for the test and discussion. It looks like am implementation issue from > >Unleash, so ... is there anything I should fix and provide a further patch? > > You're welcome to fix BBL if you want, but that's unrelated to this patch > set. I'm going to look over the code again as soon as I get a chance to, > thanks for submitting the patches! 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