Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbdLCCDJ (ORCPT ); Sat, 2 Dec 2017 21:03:09 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:2195 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752507AbdLCCDH (ORCPT ); Sat, 2 Dec 2017 21:03:07 -0500 From: Wang Nan To: , , , , CC: Wang Nan Subject: [PATCH v2 6/8] perf mmap: Fix perf backward recording Date: Sun, 3 Dec 2017 02:00:42 +0000 Message-ID: <20171203020044.81680-7-wangnan0@huawei.com> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20171203020044.81680-1-wangnan0@huawei.com> References: <20171203020044.81680-1-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6329 Lines: 130 perf record backward recording doesn't work as we expected: it never overwrite when ring buffer full. Test: (Run a busy printing task background like this: while True: print 123 send SIGUSR2 to perf to capture snapshot.) # ./perf record --overwrite -e raw_syscalls:sys_enter -e raw_syscalls:sys_exit --exclude-perf -a --switch-output [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2017110101520743 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2017110101521251 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2017110101521692 ] ^C[ perf record: Woken up 1 times to write data ] [ perf record: Dump perf.data.2017110101521936 ] [ perf record: Captured and wrote 0.826 MB perf.data. ] # ./perf script -i ./perf.data.2017110101520743 | head -n3 perf 2717 [000] 12449.310785: raw_syscalls:sys_enter: NR 16 (5, 2400, 0, 59, 100, 0) perf 2717 [000] 12449.310790: raw_syscalls:sys_enter: NR 7 (4112340, 2, ffffffff, 3df, 100, 0) python 2545 [000] 12449.310800: raw_syscalls:sys_exit: NR 1 = 4 # ./perf script -i ./perf.data.2017110101521251 | head -n3 perf 2717 [000] 12449.310785: raw_syscalls:sys_enter: NR 16 (5, 2400, 0, 59, 100, 0) perf 2717 [000] 12449.310790: raw_syscalls:sys_enter: NR 7 (4112340, 2, ffffffff, 3df, 100, 0) python 2545 [000] 12449.310800: raw_syscalls:sys_exit: NR 1 = 4 # ./perf script -i ./perf.data.2017110101521692 | head -n3 perf 2717 [000] 12449.310785: raw_syscalls:sys_enter: NR 16 (5, 2400, 0, 59, 100, 0) perf 2717 [000] 12449.310790: raw_syscalls:sys_enter: NR 7 (4112340, 2, ffffffff, 3df, 100, 0) python 2545 [000] 12449.310800: raw_syscalls:sys_exit: NR 1 = 4 Timestamps are never change, but my background task is a dead loop, can easily overwhelme the ring buffer. This patch fix it by force unsetting PROT_WRITE for backward ring buffer, so all backward ring buffer become overwrite ring buffer. Test result: # ./perf record --overwrite -e raw_syscalls:sys_enter -e raw_syscalls:sys_exit --exclude-perf -a --switch-output [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2017110101285323 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2017110101290053 ] [ perf record: dump data: Woken up 1 times ] [ perf record: Dump perf.data.2017110101290446 ] ^C[ perf record: Woken up 1 times to write data ] [ perf record: Dump perf.data.2017110101290837 ] [ perf record: Captured and wrote 0.826 MB perf.data. ] # ./perf script -i ./perf.data.2017110101285323 | head -n3 python 2545 [000] 11064.268083: raw_syscalls:sys_exit: NR 1 = 4 python 2545 [000] 11064.268084: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0) python 2545 [000] 11064.268086: raw_syscalls:sys_exit: NR 1 = 4 # ./perf script -i ./perf.data.2017110101290 | head -n3 failed to open ./perf.data.2017110101290: No such file or directory # ./perf script -i ./perf.data.2017110101290053 | head -n3 python 2545 [000] 11071.564062: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0) python 2545 [000] 11071.564064: raw_syscalls:sys_exit: NR 1 = 4 python 2545 [000] 11071.564066: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0) # ./perf script -i ./perf.data.2017110101290 | head -n3 perf.data.2017110101290053 perf.data.2017110101290446 perf.data.2017110101290837 # ./perf script -i ./perf.data.2017110101290446 | head -n3 sshd 1321 [000] 11075.499473: raw_syscalls:sys_exit: NR 14 = 0 sshd 1321 [000] 11075.499474: raw_syscalls:sys_enter: NR 14 (2, 7ffe98899490, 0, 8, 0, 3000) sshd 1321 [000] 11075.499474: raw_syscalls:sys_exit: NR 14 = 0 # ./perf script -i ./perf.data.2017110101290837 | head -n3 python 2545 [000] 11079.280844: raw_syscalls:sys_exit: NR 1 = 4 python 2545 [000] 11079.280847: raw_syscalls:sys_enter: NR 1 (1, 12cc330, 4, 7fc237280370, 7fc2373d0700, 2c7b0) python 2545 [000] 11079.280850: raw_syscalls:sys_exit: NR 1 = 4 Signed-off-by: Wang Nan --- tools/perf/util/evlist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 68c1f95..bb70aef 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -799,7 +799,7 @@ perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused, } static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, - struct mmap_params *mp, int cpu_idx, + struct mmap_params mp, int cpu_idx, int thread, int *_output, int *_output_backward) { struct perf_evsel *evsel; @@ -824,6 +824,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, if (evlist->bkw_mmap_state == BKW_MMAP_NOTREADY) perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING); } + mp.prot &= ~PROT_WRITE; } if (evsel->system_wide && thread) @@ -838,7 +839,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, if (*output == -1) { *output = fd; - if (perf_mmap__mmap(&maps[idx], mp, *output) < 0) + if (perf_mmap__mmap(&maps[idx], &mp, *output) < 0) return -1; } else { if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0) @@ -890,7 +891,7 @@ static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist, true); for (thread = 0; thread < nr_threads; thread++) { - if (perf_evlist__mmap_per_evsel(evlist, cpu, mp, cpu, + if (perf_evlist__mmap_per_evsel(evlist, cpu, *mp, cpu, thread, &output, &output_backward)) goto out_unmap; } @@ -917,7 +918,7 @@ static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, thread, false); - if (perf_evlist__mmap_per_evsel(evlist, thread, mp, 0, thread, + if (perf_evlist__mmap_per_evsel(evlist, thread, *mp, 0, thread, &output, &output_backward)) goto out_unmap; } -- 2.10.1