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[209.132.180.67]) by mx.google.com with ESMTP id hq10si3944393pac.3.2016.05.23.15.05.15; Mon, 23 May 2016 15:05:15 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753276AbcEWWFL (ORCPT + 30 others); Mon, 23 May 2016 18:05:11 -0400 Received: from merlin.infradead.org ([205.233.59.134]:42187 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752924AbcEWWDq (ORCPT ); Mon, 23 May 2016 18:03:46 -0400 Received: from [187.65.121.17] (helo=jouet.infradead.org) by merlin.infradead.org with esmtpsa (Exim 4.85_2 #1 (Red Hat Linux)) id 1b4xwm-0005bT-IF; Mon, 23 May 2016 22:03:36 +0000 Received: by jouet.infradead.org (Postfix, from userid 1000) id 0F2EA1438D1; Mon, 23 May 2016 19:03:31 -0300 (BRT) From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Wang Nan , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , Zefan Li , pi3orama@163.com, He Kuang , Arnaldo Carvalho de Melo Subject: [PATCH 9/9] perf record: Read from backward ring buffer Date: Mon, 23 May 2016 19:03:28 -0300 Message-Id: <1464041008-4825-10-git-send-email-acme@kernel.org> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1464041008-4825-1-git-send-email-acme@kernel.org> References: <1464041008-4825-1-git-send-email-acme@kernel.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Wang Nan Introduce rb_find_range() to find start and end position from a backward ring buffer. Signed-off-by: Wang Nan Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1463987628-163563-5-git-send-email-wangnan0@huawei.com Signed-off-by: He Kuang Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-record.c | 52 +++++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/evlist.c | 1 + tools/perf/util/evlist.h | 1 + 3 files changed, 54 insertions(+) -- 2.5.5 diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 73ce651c84f6..dc3fcb597e4c 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -83,6 +83,54 @@ static int process_synthesized_event(struct perf_tool *tool, return record__write(rec, event, event->header.size); } +static int +backward_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end) +{ + struct perf_event_header *pheader; + u64 evt_head = head; + int size = mask + 1; + + pr_debug2("backward_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head); + pheader = (struct perf_event_header *)(buf + (head & mask)); + *start = head; + while (true) { + if (evt_head - head >= (unsigned int)size) { + pr_debug("Finshed reading backward ring buffer: rewind\n"); + if (evt_head - head > (unsigned int)size) + evt_head -= pheader->size; + *end = evt_head; + return 0; + } + + pheader = (struct perf_event_header *)(buf + (evt_head & mask)); + + if (pheader->size == 0) { + pr_debug("Finshed reading backward ring buffer: get start\n"); + *end = evt_head; + return 0; + } + + evt_head += pheader->size; + pr_debug3("move evt_head: %"PRIx64"\n", evt_head); + } + WARN_ONCE(1, "Shouldn't get here\n"); + return -1; +} + +static int +rb_find_range(struct perf_evlist *evlist, + void *data, int mask, u64 head, u64 old, + u64 *start, u64 *end) +{ + if (!evlist->backward) { + *start = old; + *end = head; + return 0; + } + + return backward_rb_find_range(data, mask, head, start, end); +} + static int record__mmap_read(struct record *rec, int idx) { struct perf_mmap *md = &rec->evlist->mmap[idx]; @@ -94,6 +142,10 @@ static int record__mmap_read(struct record *rec, int idx) void *buf; int rc = 0; + if (rb_find_range(rec->evlist, data, md->mask, head, + old, &start, &end)) + return -1; + if (start == end) return 0; diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 904523a2be90..e82ba90cc969 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -44,6 +44,7 @@ void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus, perf_evlist__set_maps(evlist, cpus, threads); fdarray__init(&evlist->pollfd, 64); evlist->workload.pid = -1; + evlist->backward = false; } struct perf_evlist *perf_evlist__new(void) diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index 97090b70976d..d740fb877ab6 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -44,6 +44,7 @@ struct perf_evlist { bool overwrite; bool enabled; bool has_user_cpus; + bool backward; size_t mmap_len; int id_pos; int is_pos;