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Miller" , He Kuang , Jiri Olsa , Li Zefan , Masami Hiramatsu , Namhyung Kim , Peter Zijlstra , , Will Deacon , , Wang Nan Subject: [PATCH 49/54] perf tools: Set write_backward attribut bit for overwrite events Date: Mon, 25 Jan 2016 09:56:36 +0000 Message-ID: <1453715801-7732-50-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1453715801-7732-1-git-send-email-wangnan0@huawei.com> References: <1453715801-7732-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020203.56A5F1A6.0073, ss=1, re=0.000, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 9f55f2d982738c7ab972ff1508968457 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org write_backward attribute makes kernel filling ring buffer from the end of it, makes reading from overwrite ring buffer possible. This patch select this attribute if evsel->overwrite is selected explicitly by user. Overwrite and write_backward are still controled separatly for legacy readonly mmap users (most of them are in perf/tests). Signed-off-by: Wang Nan Signed-off-by: He Kuang Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Zefan Li Cc: pi3orama@163.com --- tools/perf/builtin-record.c | 7 +++++++ tools/perf/util/evlist.c | 2 ++ tools/perf/util/evlist.h | 1 + tools/perf/util/evsel.c | 13 +++++++++++++ 4 files changed, 23 insertions(+) -- 1.8.3.4 diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index f416296..09aa4ee 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -332,6 +332,13 @@ static int record__open(struct record *rec) perf_evlist__config(evlist, opts); evlist__for_each(evlist, pos) { + if (pos->overwrite) { + if (!pos->attr.write_backward) { + ui__warning("Unable to read from overwrite ring buffer\n\n"); + rc = -ENOSYS; + goto out; + } + } try_again: if (perf_evsel__open(pos, pos->cpus, pos->threads) < 0) { if (perf_evsel__fallback(pos, errno, msg, sizeof(msg))) { diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 3c308a7..807930b 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -973,6 +973,8 @@ perf_evlist__channel_for_evsel(struct perf_evsel *evsel) if (evsel->overwrite) flag |= PERF_EVLIST__CHANNEL_RDONLY; + if (evsel->attr.write_backward) + flag |= PERF_EVLIST__CHANNEL_BACKWARD; return flag; } diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index 21a8b85..321224c 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -24,6 +24,7 @@ struct record_opts; enum perf_evlist_mmap_flag { PERF_EVLIST__CHANNEL_ENABLED = 1, PERF_EVLIST__CHANNEL_RDONLY = 2, + PERF_EVLIST__CHANNEL_BACKWARD = 4, }; /** diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index d9b1f1d..d821556 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -678,6 +678,19 @@ static void apply_config_terms(struct perf_evsel *evsel, } } + /* + * Set backward after config term processing because it is + * possible to set overwrite globally, without config + * terms. + */ + if (evsel->overwrite) { + if (opts->has_write_backward) + attr->write_backward = 1; + else + pr_err("Reading from overwrite event %s is not supported\n", + evsel->name); + } + /* User explicitly set per-event callgraph, clear the old setting and reset. */ if ((callgraph_buf != NULL) || (dump_size > 0)) {