From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754617AbdKAMkC (ORCPT ); Wed, 1 Nov 2017 08:40:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41680 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754336AbdKAMkA (ORCPT ); Wed, 1 Nov 2017 08:40:00 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 6E89280F75 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jolsa@redhat.com Date: Wed, 1 Nov 2017 13:39:57 +0100 From: Jiri Olsa To: "Wangnan (F)" Cc: Namhyung Kim , linux-kernel@vger.kernel.org, kan.liang@intel.com, acme@kernel.org, kernel-team@lge.com Subject: Re: [PATCH 1/2] perf mmap: Fix perf backward recording Message-ID: <20171101123957.GA27215@krava> References: <20171101055327.141281-1-wangnan0@huawei.com> <20171101055327.141281-2-wangnan0@huawei.com> <20171101094929.GB25146@danjae.aot.lge.com> <20171101120007.GA26623@danjae.aot.lge.com> <109f02ef-5dc2-94f9-e850-572c498781ee@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <109f02ef-5dc2-94f9-e850-572c498781ee@huawei.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 01 Nov 2017 12:40:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 01, 2017 at 08:10:49PM +0800, Wangnan (F) wrote: SNIP > > > > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c > > > > index c6c891e154a6..27ebe355e794 100644 > > > > --- a/tools/perf/util/evlist.c > > > > +++ b/tools/perf/util/evlist.c > > > > @@ -838,6 +838,11 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, > > > > if (*output == -1) { > > > > *output = fd; > > > > + if (evsel->attr.write_backward) > > > > + mp->prot = PROT_READ; > > > > + else > > > > + mp->prot = PROT_READ | PROT_WRITE; > > > > + > > > If evlist->overwrite is true, PROT_WRITE should be unset even if > > > write_backward is > > > not set. If you want to delay the setting of mp->prot, you need to consider > > > both evlist->overwrite and evsel->attr.write_backward. > > I thought evsel->attr.write_backward should be set when > > evlist->overwrite is set. Do you mean following case? > > > > perf record --overwrite -e 'cycles/no-overwrite/' > > > > No. evlist->overwrite is unrelated to '--overwrite'. This is why I > said the concept of 'overwrite' and 'backward' is ambiguous. > > perf record never sets 'evlist->overwrite'. What '--overwrite' actually > does is setting write_backward. Some testcases needs overwrite evlist. did not check deeply, but so why can't we do the below? jirka --- diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index f4d9fc54b382..4643c487bd29 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -300,7 +300,7 @@ static int record__mmap_evlist(struct record *rec, struct record_opts *opts = &rec->opts; char msg[512]; - if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, false, + if (perf_evlist__mmap_ex(evlist, opts->mmap_pages, opts->overwrite, opts->auxtrace_mmap_pages, opts->auxtrace_snapshot_mode) < 0) { if (errno == EPERM) {