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Date: Wed, 12 Aug 2020 08:16:57 -0700 From: Eric Dumazet <eric.dumazet@...il.com> To: sedat.dilek@...il.com, Eric Dumazet <edumazet@...gle.com> Cc: netdev@...r.kernel.org Subject: Re: Flaw in "random32: update the net random state on interrupt and activity" On 8/11/20 11:03 PM, Sedat Dilek wrote: > [ CC netdev ] > [ Please CC me I am not subscribed to this mailing-list ] > > Hi Eric, > > I have added your diffs from [0] and have some troubles to display the > prandom_32 trace-events (I mostly followed [1]): > > I did: > > echo prandom_u32 >> /sys/kernel/debug/tracing/set_event > echo traceon > /sys/kernel/debug/tracing/events/random/prandom_u32/trigger > echo 1 > /sys/kernel/debug/tracing/events/enable > > cat /sys/kernel/debug/tracing/set_event | grep prandom > random:prandom_u32 > cat /sys/kernel/debug/tracing/events/random/prandom_u32/trigger > traceon:unlimited > cat /sys/kernel/debug/tracing/events/enable > X > > Following [2] and [3] I wanted to use perf: > > # /home/dileks/bin/perf list | grep prandom > random:prandom_u32 [Tracepoint event] > > Following the example in [4]: > > # /home/dileks/bin/perf probe --add tcp_sendmsg > # /home/dileks/bin/perf record -e probe:tcp_sendmsg -a -g -- sleep 10 > # /home/dileks/bin/perf report --stdio > > That gives me a report. > > Adapting: > > # /home/dileks/bin/perf probe --add tcp_conn_request > > # /home/dileks/bin/perf list | grep probe: > probe:tcp_conn_request [Tracepoint event] > probe:tcp_sendmsg [Tracepoint event] > > # home/dileks/bin/perf record -e probe:tcp_conn_request -a -g -- sleep 10 > > # /home/dileks/bin/perf report --stdio > Error: > The perf.data data has no samples! > # To display the perf.data header info, please use > --header/--header-only options. > # > > # /home/dileks/bin/perf report --stdio --header-only > # ======== > # captured on : Wed Aug 12 07:39:42 2020 > # header version : 1 > # data offset : 440 > # data size : 2123144 > # feat offset : 2123584 > # hostname : iniza > # os release : 5.8.1-2-amd64-llvm11-ias > # perf version : 5.8.1 > # arch : x86_64 > # nrcpus online : 4 > # nrcpus avail : 4 > # cpudesc : Intel(R) Core(TM) i5-2467M CPU @ 1.60GHz > # cpuid : GenuineIntel,6,42,7 > # total memory : 8046012 kB > # cmdline : /home/dileks/bin/perf record -e probe:tcp_conn_request -a > -g -- sleep 10 > # event : name = probe:tcp_conn_request, , id = { 304, 305, 306, 307 > }, type = 2, size = 120, config = 0x866, { sample_period, sample_freq > } = 1, sample_type = IP|TID|TIME|CALLCHAIN|CPU|PERIO> > # event : name = dummy:HG, , id = { 308, 309, 310, 311 }, type = 1, > size = 120, config = 0x9, { sample_period, sample_freq } = 4000, > sample_type = IP|TID|TIME|CALLCHAIN|CPU|PERIOD|IDENTIFIER,> > # CPU_TOPOLOGY info available, use -I to display > # NUMA_TOPOLOGY info available, use -I to display > # pmu mappings: software = 1, power = 14, uprobe = 7, cpu = 4, > cstate_core = 12, breakpoint = 5, uncore_cbox_0 = 9, tracepoint = 2, > cstate_pkg = 13, uncore_arb = 11, kprobe = 6, i915 = 15, ms> > # CACHE info available, use -I to display > # time of first sample : 0.000000 > # time of last sample : 0.000000 > # sample duration : 0.000 ms > # MEM_TOPOLOGY info available, use -I to display > # bpf_prog_info 3: bpf_prog_6deef7357e7b4530 addr 0xffffffffc01d7834 size 66 > # bpf_prog_info 4: bpf_prog_6deef7357e7b4530 addr 0xffffffffc01df7e8 size 66 > # bpf_prog_info 5: bpf_prog_6deef7357e7b4530 addr 0xffffffffc041ca18 size 66 > # bpf_prog_info 6: bpf_prog_6deef7357e7b4530 addr 0xffffffffc041eb58 size 66 > # bpf_prog_info 7: bpf_prog_6deef7357e7b4530 addr 0xffffffffc1061dc0 size 66 > # bpf_prog_info 8: bpf_prog_6deef7357e7b4530 addr 0xffffffffc1063388 size 66 > # bpf_prog_info 12: bpf_prog_6deef7357e7b4530 addr 0xffffffffc129c244 size 66 > # bpf_prog_info 13: bpf_prog_6deef7357e7b4530 addr 0xffffffffc129e8c0 size 66 > # cpu pmu capabilities: branches=16, max_precise=2, pmu_name=sandybridge > # missing features: BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID > DIR_FORMAT COMPRESSED > # ======== > # > > In dmesg I see: > > [Wed Aug 12 07:30:52 2020] Scheduler tracepoints stat_sleep, > stat_iowait, stat_blocked and stat_runtime require the kernel > parameter schedstats=enable or kernel.sched_schedstats=1 > > CONFIG_SCHEDSTATS=y is set. > > # echo 1 > /proc/sys/kernel/sched_schedstats > # cat /proc/sys/kernel/sched_schedstats > 1 > > Still seeing: > # /home/dileks/bin/perf report --stdio > Error: > The perf.data data has no samples! > # To display the perf.data header info, please use > --header/--header-only options. > # > > Do I miss to set some required Kconfigs? > I have attached my latest kernel-config file. > > So I need a helping hand how to trace prandom_u32 events in general? perf record -a -g -e random:prandom_u32 sleep 5 Then something like perf report --no-children or "perf script" > > How to add it as a kernel-boot-parameter (see [4])? > > Any help appreciated and thanks in advance. > > Thanks. > > Regards, > - Sedat - > > [0] https://marc.info/?l=linux-netdev&m=159716173516111&w=2 > [1] https://www.kernel.org/doc/html/v5.8/trace/events.html > [2] http://www.brendangregg.com/perf.html > [3] http://www.brendangregg.com/perf.html#DynamicTracing > [4] https://www.kernel.org/doc/html/v5.8/trace/events.html#boot-option >
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