Messages in this thread | | | Date | Wed, 24 Feb 2016 10:36:37 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 10/48] perf tools: Introduce bpf-output event |
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Em Wed, Feb 24, 2016 at 09:58:34AM +0800, Wangnan (F) escreveu: > > > On 2016/2/24 1:45, Arnaldo Carvalho de Melo wrote: > >Em Mon, Feb 22, 2016 at 09:10:37AM +0000, Wang Nan escreveu: > >>Commit a43eec304259a6c637f4014a6d4767159b6a3aa3 (bpf: introduce > >>bpf_perf_event_output() helper) add a helper to enable BPF program > >>output data to perf ring buffer through a new type of perf event > >>PERF_COUNT_SW_BPF_OUTPUT. This patch enable perf to create perf > >>event of that type. Now perf user can use following cmdline to > >>receive output data from BPF programs: > >> > >> # ./perf record -a -e bpf-output/no-inherit,name=evt/ \ > >> -e ./test_bpf_output.c/map:channel.event=evt/ ls / > >> # ./perf script > >> perf 1560 [004] 347747.086295: evt: ffffffff811fd201 sys_write ... > >> perf 1560 [004] 347747.086300: evt: ffffffff811fd201 sys_write ... > >> perf 1560 [004] 347747.086315: evt: ffffffff811fd201 sys_write ... > >> ... > >> > >>Test result: > >> # cat ./test_bpf_output.c > >> /************************ BEGIN **************************/ > >> #include <uapi/linux/bpf.h> > >> struct bpf_map_def { > >> unsigned int type; > >> unsigned int key_size; > >> unsigned int value_size; > >> unsigned int max_entries; > >> }; > >> > >> #define SEC(NAME) __attribute__((section(NAME), used)) > >> static u64 (*ktime_get_ns)(void) = > >> (void *)BPF_FUNC_ktime_get_ns; > >> static int (*trace_printk)(const char *fmt, int fmt_size, ...) = > >> (void *)BPF_FUNC_trace_printk; > >> static int (*get_smp_processor_id)(void) = > >> (void *)BPF_FUNC_get_smp_processor_id; > >> static int (*perf_event_output)(void *, struct bpf_map_def *, int, void *, unsigned long) = > >> (void *)BPF_FUNC_perf_event_output; > >> > >> struct bpf_map_def SEC("maps") channel = { > >> .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY, > >> .key_size = sizeof(int), > >> .value_size = sizeof(u32), > >> .max_entries = __NR_CPUS__, > >> }; > >> > >> SEC("func_write=sys_write") > >> int func_write(void *ctx) > >> { > >> struct { > >> u64 ktime; > >> int cpuid; > >> } __attribute__((packed)) output_data; > >> char error_data[] = "Error: failed to output: %d\n"; > >> > >> output_data.cpuid = get_smp_processor_id(); > >> output_data.ktime = ktime_get_ns(); > >> int err = perf_event_output(ctx, &channel, get_smp_processor_id(), > >> &output_data, sizeof(output_data)); > >> if (err) > >> trace_printk(error_data, sizeof(error_data), err); > >> return 0; > >> } > >> char _license[] SEC("license") = "GPL"; > >> int _version SEC("version") = LINUX_VERSION_CODE; > >> /************************ END ***************************/ > >> > >> # ./perf record -a -e bpf-output/no-inherit,name=evt/ \ > >> -e ./test_bpf_output.c/map:channel.event=evt/ ls / > >> # ./perf script | grep ls > >> ls 2242 [003] 347851.557563: evt: ffffffff811fd201 sys_write ... > >> ls 2242 [003] 347851.557571: evt: ffffffff811fd201 sys_write ... > >So, there is something strange here: > > > > if (unlikely(event->oncpu != smp_processor_id())) > > return -EOPNOTSUPP; > > > >This is where I am hitting, with: > > > >[acme@jouet linux]$ uname -r > >4.5.0-rc4 > > > > int err = perf_event_output(ctx, &channel, get_smp_processor_id(), > > &output_data, sizeof(output_data)); > > if (err) > > trace_printk(error_data, sizeof(error_data), err); > > > >And then: > > > >[root@jouet bpf]# tail /sys/kernel/debug/tracing/trace > > perf-13040 [003] d... 12062.807729: : Error: failed to output: -95 > > perf-13040 [003] d... 12062.807731: : Error: failed to output: -95 > > perf-13040 [003] d... 12062.807732: : Error: failed to output: -95 > > perf-13040 [003] d... 12062.807735: : Error: failed to output: -95 > > perf-13040 [003] d... 12062.807737: : Error: failed to output: -95 > > perf-13040 [003] d... 12062.807744: : Error: failed to output: -95 > > gnome-terminal--3091 [001] d... 12062.807773: : Error: failed to output: -95 > > gnome-terminal--3091 [001] d... 12062.807784: : Error: failed to output: -95 > > gmain-2830 [002] d... 12062.811791: : Error: failed to output: -95 > > gmain-2830 [002] d... 12062.811810: : Error: failed to output: -95 > >[root@jouet bpf]# > > > >Ideas? AFK for a while, will continue investigating. > > I also noticed this output, but didn't digg into it because all events > I concerned is okay. I'll look into this today. > > >This already was submitted to Ingo, BTW. > > > >I used, as in the changeset comment tests: > > > >perf record -a -e bpf-output/no-inherit,name=evt/ -e ./test_bpf_output.c/map:channel.event=evt/ ls / > > > >And perf script told me: > > > >[root@jouet bpf]# perf script | tail > > perf 13040 [003] 12062.708337: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708339: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708340: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708341: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708343: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708344: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708346: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708347: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708348: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > > perf 13040 [003] 12062.708350: evt: ffffffff81234eb1 sys_write (/lib/modules/4.5.0-rc4/build/vmlinux) > >[root@jouet bpf]# > > > >Wonder where that /lib/modules/4.5.0-rc4/build/vmlinux came from... > > > >[root@jouet bpf]# perf script | cut -d'(' -f2 | sort | uniq -c > > 1141 /lib/modules/4.5.0-rc4/build/vmlinux) > > It's a standard directory for perf searching vmlinux. Isn't it?
Nah, that was me being confused by 'perf script's output, it looked like what was enclosed in () right after the sys_write was a parameter for that function (sys_write), when in fact it is the DSO where sys_write is in, duh.
- Arnaldo
> tools/perf/util/symbol.c: > > static const char * const vmlinux_paths_upd[] = { > "/boot/vmlinux-%s", > "/usr/lib/debug/boot/vmlinux-%s", > "/lib/modules/%s/build/vmlinux", > "/usr/lib/debug/lib/modules/%s/vmlinux", > "/usr/lib/debug/boot/vmlinux-%s.debug" > }; > > So what's your problem? > > Thank you.
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