From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49DD6C433DF for ; Wed, 29 Jul 2020 07:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2EC2C2076E for ; Wed, 29 Jul 2020 07:23:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727855AbgG2HXT (ORCPT ); Wed, 29 Jul 2020 03:23:19 -0400 Received: from mga04.intel.com ([192.55.52.120]:23959 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727112AbgG2HXS (ORCPT ); Wed, 29 Jul 2020 03:23:18 -0400 IronPort-SDR: p5+omKWVjITymiqCHJ1piW63LXyJ+Lpbbk+9s7vHNKnTuk0JINccEmu1Bh2xH85RKUU64rRJXl g4D3gTxsPJoQ== X-IronPort-AV: E=McAfee;i="6000,8403,9696"; a="148829886" X-IronPort-AV: E=Sophos;i="5.75,409,1589266800"; d="scan'208";a="148829886" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jul 2020 00:23:16 -0700 IronPort-SDR: GynbTJcHPsM4btdfc36s/y1JeLAoJOMRZnFrmbJM9Eq8ZwK1IUndL3PhS0Sr2E45mHEkap/iE5 86+1nLLUNx+w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,409,1589266800"; d="scan'208";a="320666570" Received: from yjin15-mobl1.ccr.corp.intel.com (HELO [10.238.5.239]) ([10.238.5.239]) by orsmga008.jf.intel.com with ESMTP; 29 Jul 2020 00:23:13 -0700 Subject: Re: [PATCH v2] perf evsel: Don't set sample_regs_intr/sample_regs_user for dummy event From: "Jin, Yao" To: Jiri Olsa , Adrian Hunter 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, irogers@google.com References: <20200720010013.18238-1-yao.jin@linux.intel.com> <20200720091748.GH760733@krava> <20200722110810.GD981884@krava> <6f732f7f-7c5a-726f-5b09-2c6761f3b534@linux.intel.com> Message-ID: Date: Wed, 29 Jul 2020 15:23:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <6f732f7f-7c5a-726f-5b09-2c6761f3b534@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Adrian, Could you help to check if following condition will break PT? "(opts->sample_intr_regs && !evsel->no_aux_samples && !evsel__is_dummy_event(evsel))" Thanks Jin Yao On 7/23/2020 9:01 AM, Jin, Yao wrote: > Hi Jiri, Adrian, > > On 7/22/2020 7:08 PM, Jiri Olsa wrote: >> On Wed, Jul 22, 2020 at 01:00:03PM +0800, Jin, Yao wrote: >> >> SNIP >> >>>>> >>>>> If we use -IXMM0, the attr>sample_regs_intr will be set with >>>>> PERF_REG_EXTENDED_MASK bit. >>>>> >>>>> It doesn't make sense to set attr->sample_regs_intr for a >>>>> software dummy event. >>>>> >>>>> This patch adds dummy event checking before setting >>>>> attr->sample_regs_intr and attr->sample_regs_user. >>>>> >>>>> After: >>>>>     # ./perf record -e cycles:p -IXMM0 -a -- sleep 1 >>>>>     [ perf record: Woken up 1 times to write data ] >>>>>     [ perf record: Captured and wrote 0.413 MB perf.data (45 samples) ] >>>>> >>>>>    v2: >>>>>    --- >>>>>    Rebase to perf/core >>>>> >>>>> Fixes: 0a892c1c9472 ("perf record: Add dummy event during system wide synthesis") >>>>> Signed-off-by: Jin Yao >>>>> --- >>>>>    tools/perf/util/evsel.c | 6 ++++-- >>>>>    1 file changed, 4 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c >>>>> index 9aa51a65593d..11794d3b7879 100644 >>>>> --- a/tools/perf/util/evsel.c >>>>> +++ b/tools/perf/util/evsel.c >>>>> @@ -1014,12 +1014,14 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts, >>>>>        if (callchain && callchain->enabled && !evsel->no_aux_samples) >>>>>            evsel__config_callchain(evsel, opts, callchain); >>>>> -    if (opts->sample_intr_regs && !evsel->no_aux_samples) { >>>>> +    if (opts->sample_intr_regs && !evsel->no_aux_samples && >>>>> +        !evsel__is_dummy_event(evsel)) { >>>> >>>> hum, I thought it'd look something like this: >>>> >>>>     if (opts->sample_intr_regs && (!evsel->no_aux_samples || !evsel__is_dummy_event(evsel)) >>>> >>>> but I'm not sure how no_aux_samples flag works exactly.. so it might be >>>> correct.. just making sure ;-) >>>> >>>> cc-ing Adrian >>>> >>>> jirka >>>> >>>> >>> >>> no_aux_samples is set to false by default and it's only set to true by pt, right? >>> >>> So most of the time, !evsel->no_aux_samples is always true. >>> >>> if (opts->sample_intr_regs && (!evsel->no_aux_samples || !evsel__is_dummy_event(evsel)) { >>>     attr->sample_regs_intr = opts->sample_intr_regs; >>>     evsel__set_sample_bit(evsel, REGS_INTR); >>> } >>> >>> So even if the evsel is dummy event, the condition check is true. :( >>> >>> Or maybe I misunderstand anything? >> >> I was just curious, because I did not follow the no_aux_samples >> usage in detail.. so how about a case where: >> >>     evsel->no_aux_samples == true and evsel__is_dummy_event(evsel) = false >> >> then the original condition will be false for non dummy event >> >>    (opts->sample_intr_regs && !evsel->no_aux_samples && !evsel__is_dummy_event(evsel)) >> >> is that ok? >> > > I searched the perf source and found the no_aux_samples was only set to true in intel-pt.c. So I > assume for the non-pt usage, the no_aux_samples is always false. > > For non-pt usage, > (opts->sample_intr_regs && !evsel->no_aux_samples && !evsel__is_dummy_event(evsel)) is equal to > (opts->sample_intr_regs && !evsel__is_dummy_event(evsel)) > > For pt usage, we need to consider the case that evsel__is_dummy_event(evsel) is true or false. > > If evsel__is_dummy_event(evsel) is true: > (opts->sample_intr_regs && !evsel->no_aux_samples && !evsel__is_dummy_event(evsel)) is false. > It's expected. > > If evsel__is_dummy_event(evsel) is false: > (opts->sample_intr_regs && !evsel->no_aux_samples && !evsel__is_dummy_event(evsel)) is equal to > (opts->sample_intr_regs && !evsel->no_aux_samples) > That's the current code logic. > > So I think the condition "(opts->sample_intr_regs && !evsel->no_aux_samples && > !evsel__is_dummy_event(evsel))" looks reasonable. > > Adrian, please correct me if I'm wrong here. > > Thanks > Jin Yao > >> jirka >>