Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FDFAC678D5 for ; Tue, 7 Mar 2023 19:54:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230012AbjCGTyJ (ORCPT ); Tue, 7 Mar 2023 14:54:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50758 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231260AbjCGTxq (ORCPT ); Tue, 7 Mar 2023 14:53:46 -0500 Received: from mail-pg1-x536.google.com (mail-pg1-x536.google.com [IPv6:2607:f8b0:4864:20::536]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92BE2A17CD; Tue, 7 Mar 2023 11:45:28 -0800 (PST) Received: by mail-pg1-x536.google.com with SMTP id h31so8285437pgl.6; Tue, 07 Mar 2023 11:45:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1678218327; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=P8WHAoxDTRRK4jgSNRWSO106FAPif1ofRn3Id2SdfTg=; b=Df7Py+r+m8TXzKdv94IMkfGQikmUBvIMX0mpKskcpWVQxBtnSYifG65S7ptSkgy4hD dyJBe3RRVpaDLcMe2/WgMbLwgSvkfcFJ15689YjlPWO6VxQFsPWh6c7CCanjgOlTKRVO ksWtvFsuzT4zUxfnzRJiIh4MLVxwo/isqPSgVBt9h8iZR53N2tvKT4bw3sDEFJ0wcKhQ LRgsGCPWQl6g8mQFruudwy+LexsvlrdKtRjto7Zde28tzAybL5vqzoMy10Stp7TGnUUj WC7QMlv2QAVsGQeiLv++s+uzRNxGeFDjyr6m9xA1j/pdVsMSIsXHPFmXmA18VpXFZQNu ZYUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678218327; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=P8WHAoxDTRRK4jgSNRWSO106FAPif1ofRn3Id2SdfTg=; b=bjNQcaQWxf/vTkr29KgQZmc9kLYSjnRG31FUd5H8+HuYZUtq+N8NNcuS21evheqBbS ov5s2PMSNUqOLxv8ZjZ6Bn4plMEMz0cAczcWquorTuQ++d3vOuNYedXN/0BUcdnNC1yn i12A6dahL7c9Ua63CJyVMk+BG1znLzp6CZHPQxAQv6NIzomb+P+FU+KIxxK/vK35KF7f al1A8CLz1WYCV+A4zLGQtyWGLYwle3uULkCtRcgXQ9tgoFJE/I/W3eaR6F+tZHPuEkkb 79zY/YWUb3P2xijQ25/XVHfSCK8GihEg8wNwrt+SxvForW8OsRqjKETq/EGzTgC5wkYs uPMQ== X-Gm-Message-State: AO0yUKXDP9SWPv3L89a5dsjjyg8hj6f5ehO/86NQwJ4n8/IJ8pMDad8I SBKpwA1b3DXHNBxDbvdn3HaU4S4rka2eR4sBspY= X-Google-Smtp-Source: AK7set8dNzbBQE8T8gnrJ4/QKDyk+bntEZEGiPqi70liTAPp0sYr6bg4WsKA8nle1I/wlCQ54LthkY82dhH9SuSP1vQ= X-Received: by 2002:a63:931e:0:b0:503:2561:6fed with SMTP id b30-20020a63931e000000b0050325616fedmr5561743pge.1.1678218327480; Tue, 07 Mar 2023 11:45:27 -0800 (PST) MIME-Version: 1.0 References: <8ca2b07e-674e-afb6-ff12-87504f51f252@arm.com> In-Reply-To: <8ca2b07e-674e-afb6-ff12-87504f51f252@arm.com> From: Yang Shi Date: Tue, 7 Mar 2023 11:45:16 -0800 Message-ID: Subject: Re: [BUG] perf: No samples found when using kcore + coresight To: James Clark Cc: linux-perf-users@vger.kernel.org, LAK , coresight@lists.linaro.org, Linux Kernel Mailing List , leo.yan@linaro.org, mathieu.poirier@linaro.org, adrian.hunter@intel.com, Jiri Olsa , acme@redhat.com, mike.leach@linaro.org, Will Deacon , suzuki.poulose@arm.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi James, Thanks for the prompt response. Please see the inline replies. On Tue, Mar 7, 2023 at 2:32=E2=80=AFAM James Clark wr= ote: > > > > On 06/03/2023 21:13, Yang Shi wrote: > > Hi, > > > > I'm seeking some help regarding perf record --kcore + coresight. When > > I tracing with perf record --kcore -e cs_etm ... , perf report shows > > "The perf.data/data data has no samples!". > > > > I tried other combinations: > > 1. perf record --kcore (w/o using coresight): works > > 2. perf record -e cs_etm ... : works > > 3. Manually copy kcore with perf buildid-cache, then run perf record > > -e cs_etm... : works > > > > So just "perf record --kcore -e cs_etm ..." doesn't work. > > > > I'm using v6.2 kernel and the perf is built from the same kernel > > source with OpenCSD 1.4. Also attached the sample file generated by > > perf. > > > > Any suggestion is appreciated. > > > > Thanks, > > Yang > > Hi Yang, > > I don't see any issue with this command and I still get samples: > > perf record -e cs_etm// --kcore -- true This command works for me. But the below command doesn't work: perf record --kcore -e cs_etm/@tmc_etf63/k --per-thread -- taskset --cpu-list 1 uname > > You might want to try running both record and report in verbose and > stdio mode (-vvv --stdio) to see if you see any warnings. > > I can't think of any way --kcore would cause an issue because all it > does is save kcore into the .debug cache rather than affecting the > actual perf.data file. Yes, this is what I thought. But digging into the code seems it may add a new dummy event. Please see the below data header dump. > > Are you running perf report in the same place the recording was made? Or > on another system? Yes. I did some further investigation. The below is the dump for both good and bad data files. Good (copy kcore manually): # captured on : Tue Mar 7 11:19:14 2023 # header version : 1 # data offset : 1576 # data size : 26736 # feat offset : 28312 # hostname : fedora # os release : 6.2.0-coresight+ # perf version : 6.2.g3424af22c4fc # arch : aarch64 # nrcpus online : 128 # nrcpus avail : 128 # cpuid : 0x00000000c00fac30 # total memory : 2108862504 kB # cmdline : /root/bin/perf record -e cs_etm/@tmc_etf63/k --kcore --per-thread -- taskset --cpu-list 1 true # event : name =3D cs_etm/@tmc_etf63/k, , id =3D { 2248 }, type =3D 9, size =3D 128, { sample_period, sample_freq } =3D 1, sample_type =3D IP|TID|IDENTIFIER, read_format =3D ID|LO ST, disabled =3D 1, exclude_user =3D 1, exclude_hv =3D 1, enable_on_exec = =3D 1, sample_id_all =3D 1, { bp_len, config2 } =3D 0x12792918 # event : name =3D dummy:u, , id =3D { 2249 }, type =3D 1, size =3D 128, config =3D 0x9, { sample_period, sample_freq } =3D 1, sample_type =3D IP|TID|IDENTIFIER, read_format =3D ID| LOST, disabled =3D 1, exclude_kernel =3D 1, exclude_hv =3D 1, mmap =3D 1, c= omm =3D 1, enable_on_exec =3D 1, task =3D 1, sample_id_all =3D 1, exclude_guest= =3D 1, mmap2 =3D 1, comm_exec =3D 1, context_switch =3D 1, bpf_event =3D 1 # event : name =3D dummy:u, , id =3D { 2250, 2251, 2252, 2253, 2254, 2255, 2256, 2257, 2258, 2259, 2260, 2261, 2262, 2263, 2264, 2265, 2266, 2267, 2268, 2269, 2270, 2271 , 2272, 2273, 2274, 2275, 2276, 2277, 2278, 2279, 2280, 2281, 2282, 2283, 2284, 2285, 2286, 2287, 2288, 2289, 2290, 2291, 2292, 2293, 2294, 2295, 2296, 2297, 2298, 2 299, 2300, 2301, 2302, 2303, 2304, 2305, 2306, 2307, 2308, 2309, 2310, 2311, 2312, 2313, 2314, 2315, 2316, 2317, 2318, 2319, 2320, 2321, 2322, 2323, 2324, 2325, 2326 , 2327, 2328, 2329, 2330, 2331, 2332, 2333, 2334, 2335, 2336, 2337, 2338, 2339, 2340, 2341, 2342, 2343, 2344, 2345, 2346, 2347, 2348, 2349, 2350, 2351, 2352, 2353, 2 354, 2355, 2356, 2357, 2358, 2359, 2360, 2361, 2362, 2363, 2364, 2365, 2366, 2367, 2368, 2369, 2370, 2371, 2372, 2373, 2374, 2375, 2376, 2377 }, type =3D 1, size =3D 128 , config =3D 0x9, { sample_period, sample_freq } =3D 1, sample_type =3D IP|TID|TIME|IDENTIFIER, read_format =3D ID|LOST, exclude_kernel =3D 1, exclude_hv =3D 1, sample_id_all =3D 1, exclude_guest =3D 1, ksymbol =3D 1, text_poke =3D 1 # CPU_TOPOLOGY info available, use -I to display # NUMA_TOPOLOGY info available, use -I to display # pmu mappings: armv8_pmuv3_0 =3D 8, software =3D 1, arm_cmn_0 =3D 10, uprobe =3D 7, cs_etm =3D 9, breakpoint =3D 5, tracepoint =3D 2, arm_cmn_1 = =3D 11, kprobe =3D 6 # contains AUX area data (e.g. instruction trace) # CACHE info available, use -I to display # time of first sample : 18446744073.709551 # time of last sample : 18446744073.709551 # sample duration : 0.000 ms # MEM_TOPOLOGY info available, use -I to display # armv8_pmuv3_0 pmu capabilities: slots=3D0x00000004, bus_slots=3D0x00000000, bus_width=3D0x00000000 # missing features: (null) CPUDESC BRANCH_STACK GROUP_DESC STAT CLOCKID DIR_FORMAT COMPRESSED CPU_PMU_CAPS CLOCK_DATA HYBRID_TOPOLOGY Bad: # captured on : Tue Mar 7 11:19:14 2023 # header version : 1 # data offset : 1576 # data size : 26736 # feat offset : 28312 # hostname : fedora # os release : 6.2.0-coresight+ # perf version : 6.2.g3424af22c4fc # arch : aarch64 # nrcpus online : 128 # nrcpus avail : 128 # cpuid : 0x00000000c00fac30 # total memory : 2108862504 kB # cmdline : /root/bin/perf record -e cs_etm/@tmc_etf63/k --kcore --per-thread -- taskset --cpu-list 1 true # event : name =3D cs_etm/@tmc_etf63/k, , id =3D { 2248 }, type =3D 9, size =3D 128, { sample_period, sample_freq } =3D 1, sample_type =3D IP|TID|IDENTIFIER, read_format =3D ID|LO ST, disabled =3D 1, exclude_user =3D 1, exclude_hv =3D 1, enable_on_exec = =3D 1, sample_id_all =3D 1, { bp_len, config2 } =3D 0x12792918 # event : name =3D dummy:u, , id =3D { 2249 }, type =3D 1, size =3D 128, config =3D 0x9, { sample_period, sample_freq } =3D 1, sample_type =3D IP|TID|IDENTIFIER, read_format =3D ID| LOST, disabled =3D 1, exclude_kernel =3D 1, exclude_hv =3D 1, mmap =3D 1, c= omm =3D 1, enable_on_exec =3D 1, task =3D 1, sample_id_all =3D 1, exclude_guest= =3D 1, mmap2 =3D 1, comm_exec =3D 1, context_switch =3D 1, bpf_event =3D 1 # event : name =3D dummy:u, , id =3D { 2250, 2251, 2252, 2253, 2254, 2255, 2256, 2257, 2258, 2259, 2260, 2261, 2262, 2263, 2264, 2265, 2266, 2267, 2268, 2269, 2270, 2271 , 2272, 2273, 2274, 2275, 2276, 2277, 2278, 2279, 2280, 2281, 2282, 2283, 2284, 2285, 2286, 2287, 2288, 2289, 2290, 2291, 2292, 2293, 2294, 2295, 2296, 2297, 2298, 2 299, 2300, 2301, 2302, 2303, 2304, 2305, 2306, 2307, 2308, 2309, 2310, 2311, 2312, 2313, 2314, 2315, 2316, 2317, 2318, 2319, 2320, 2321, 2322, 2323, 2324, 2325, 2326 , 2327, 2328, 2329, 2330, 2331, 2332, 2333, 2334, 2335, 2336, 2337, 2338, 2339, 2340, 2341, 2342, 2343, 2344, 2345, 2346, 2347, 2348, 2349, 2350, 2351, 2352, 2353, 2 354, 2355, 2356, 2357, 2358, 2359, 2360, 2361, 2362, 2363, 2364, 2365, 2366, 2367, 2368, 2369, 2370, 2371, 2372, 2373, 2374, 2375, 2376, 2377 }, type =3D 1, size =3D 128 , config =3D 0x9, { sample_period, sample_freq } =3D 1, sample_type =3D IP|TID|TIME|IDENTIFIER, read_format =3D ID|LOST, exclude_kernel =3D 1, exclude_hv =3D 1, sample_id_all =3D 1, exclude_guest =3D 1, ksymbol =3D 1, text_poke =3D 1 # CPU_TOPOLOGY info available, use -I to display # NUMA_TOPOLOGY info available, use -I to display # pmu mappings: armv8_pmuv3_0 =3D 8, software =3D 1, arm_cmn_0 =3D 10, uprobe =3D 7, cs_etm =3D 9, breakpoint =3D 5, tracepoint =3D 2, arm_cmn_1 = =3D 11, kprobe =3D 6 # contains AUX area data (e.g. instruction trace) # CACHE info available, use -I to display # time of first sample : 18446744073.709551 # time of last sample : 18446744073.709551 # sample duration : 0.000 ms # MEM_TOPOLOGY info available, use -I to display # armv8_pmuv3_0 pmu capabilities: slots=3D0x00000004, bus_slots=3D0x00000000, bus_width=3D0x00000000 # missing features: (null) CPUDESC BRANCH_STACK GROUP_DESC STAT CLOCKID DIR_FORMAT COMPRESSED CPU_PMU_CAPS CLOCK_DATA HYBRID_TOPOLOGY Dumping raw events could show the events from the bad data file. But it has zero samples after event collapse. The only difference is --kcore inserted a new text_poke dummy event. It seems coresight also inserted a dummy event with my command but your command didn't. So it seems like the two dummy events confused event collapse. The text_poke dummy event is added by commit f42c0ce573df79d1b8bd169008c994dcdd43585a ("perf record: Always get text_poke events with --kcore option"). If I reverted this commit, then it works. But I'm not sure whether this is the right fix or real root cause or not. Or coresight shouldn't insert its own dummy event? > > James