> On Apr 26, 2019, at 11:37 AM, Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx> wrote: > > tldr; more to the end there are some annotation for all sorts of cache level > misses trying to validate the 'perf annotation' output for disassembled > BPF programs. > > [root@quaco ~]# uname -a > Linux quaco 5.1.0-rc5+ #4 SMP Wed Apr 17 19:33:00 -03 2019 x86_64 x86_64 x86_64 GNU/Linux > > Running perf trace with: > > [root@quaco ~]# cat ~/.perfconfig > [llvm] > dump-obj = true > clang-opt = -g > [trace] > add_events = /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.c > #add_events = /wb/augmented_raw_syscalls.o > show_zeros = yes > show_duration = no > no_inherit = yes > show_timestamp = no > show_arg_names = no > args_alignment = 40 > show_prefix = yes > > [annotate] > > hide_src_code = false > [root@quaco ~]# > > clang/llvm 9: > > [root@quaco perf]# eu-readelf -winfo /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.o | grep compile_unit > [ b] compile_unit abbrev: 1 > [root@quaco perf]# eu-readelf -winfo /home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.o | grep compile_unit -B1 -A10 > Version: 4, Abbreviation section offset: 0, Address size: 8, Offset size: 4 > [ b] compile_unit abbrev: 1 > producer (strp) "clang version 9.0.0 (https://urldefense.proofpoint.com/v2/url?u=https-3A__git.llvm.org_git_clang.git_&d=DwIDaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=8ymLhVNE6vfRn0KCyz7xlPkm7i1H4ttMrMYmeHEP1Cg&s=3_k_sPaZo7mwxQMoYhgd4hBUmCoS3TboKrw15yws6mA&e= 7906282d3afec5dfdc2b27943fd6c0309086c507) (https://urldefense.proofpoint.com/v2/url?u=https-3A__git.llvm.org_git_llvm.git_&d=DwIDaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=8ymLhVNE6vfRn0KCyz7xlPkm7i1H4ttMrMYmeHEP1Cg&s=jutQ4xaAa5FePXthz5gHAgdx6kVlrPI64pnpqWWt59Q&e= a1b5de1ff8ae8bc79dc8e86e1f82565229bd0500)" > language (data2) C99 (12) > name (strp) "/home/acme/git/perf/tools/perf/examples/bpf/augmented_raw_syscalls.c" > stmt_list (sec_offset) 0 > comp_dir (strp) "/root" > low_pc (addr) raw_syscalls:sys_enter+000000000000000000 <sys_enter> > ranges (sec_offset) range list [ 0] > [ 2a] variable abbrev: 2 > name (strp) "__augmented_syscalls__" > type (ref4) [ 3f] > [root@quaco perf]# > > I then leave this running doing system wide syscall tracing using that > augmented_raw_syscalls.c eBPF program hooked into the syscall enter and > exit tracepoints, so that I have something to profile and further test > the BPF support in perf top/annotate/report (slides for LSFMM anyone? > :-)) then I get: > > # perf trace -a sleep 100h wow, I never tried to run sleep with "100h". ;-) > <SNIP> > tmux: server/11597 ioctl(8</dev/ptmx>, TIOCLINUX, 0x7ffe1b49abf8) = 0 > tmux: server/11597 readv(8, 0x7ffe1b49ac00, 1) = 101 > tmux: server/11597 ioctl(8</dev/ptmx>, TIOCSPGRP, 0x7ffe1b49a9f4) = 0 > tmux: server/11597 openat(AT_FDCWD, "/proc/30339/cmdline", O_RDONLY) = 5 > tmux: server/11597 fstat(5, 0x7ffe1b49a8e0) = 0 > tmux: server/11597 read(5, 0x5571aaeb2c10, 1024) = 10 > tmux: server/11597 close(5) = 0 > gnome-shell/19195 ... [continued]: ioctl()) = 0 > tmux: server/11597 poll(0x5571aad38e50, 6, 11997) ... > gnome-shell/19195 ioctl(11</dev/dri/card0>, DRM_MODE_RMFB, 0x7ffc2129c25c) = 0 > gnome-shell/19195 recvmsg(39<socket:[18671390]>, 0x7ffc2129c440, NONE) = -1 EAGAIN (Resource temporarily unavailable) > <SNIP> > > With that running, I do: > > [root@quaco perf]# perf record -a sleep 2s > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 1.647 MB perf.data (3698 samples) ] > [root@quaco perf]# > > I.e. collect 2 seconds worth of CPU cycles samples, system wide. > > [root@quaco perf]# perf record -a sleep 2s > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 2.328 MB perf.data (17764 samples) ] > [root@quaco perf]# perf report --header-only perf.data | grep -i b[pt]f > # event : name = cycles, , id = { 266608, 266609, 266610, 266611, 266612, 266613, 266614, 266615 }, size = 112, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|CPU|PERIOD, read_format = ID, disabled = 1, inherit = 1, mmap = 1, comm = 1, freq = 1, task = 1, precise_ip = 3, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1, ksymbol = 1, bpf_event = 1 > # bpf_prog_info 13: bpf_prog_7be49e3934a125ba addr 0xffffffffc0437f01 size 229 > # bpf_prog_info 14: bpf_prog_2a142ef67aaad174 addr 0xffffffffc04393cd size 229 > # bpf_prog_info 17: bpf_prog_7be49e3934a125ba addr 0xffffffffc052ca3c size 229 > # bpf_prog_info 18: bpf_prog_2a142ef67aaad174 addr 0xffffffffc0531218 size 229 > # bpf_prog_info 21: bpf_prog_7be49e3934a125ba addr 0xffffffffc0cb8010 size 229 > # bpf_prog_info 22: bpf_prog_2a142ef67aaad174 addr 0xffffffffc0cba8be size 229 > # bpf_prog_info 65: bpf_prog_7be49e3934a125ba addr 0xffffffffc03f6bc2 size 229 > # bpf_prog_info 66: bpf_prog_2a142ef67aaad174 addr 0xffffffffc03f87f6 size 229 > # bpf_prog_info 125: bpf_prog_819967866022f1e1_sys_enter addr 0xffffffffc0c6e5a1 size 381 > # bpf_prog_info 126: bpf_prog_c1bd85c092d6e4aa_sys_exit addr 0xffffffffc0c953a8 size 191 > [root@quaco perf]# > > So everything seems in order, but then: > > [root@quaco perf]# perf report | grep bpf_prog > 0.14% perf bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.08% gnome-terminal- bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > 0.06% perf bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > 0.04% gnome-terminal- bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.01% alsa-sink-ALC25 bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > 0.01% Web Content bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.01% lvmetad bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > 0.00% alsa-sink-ALC25 bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.00% sssd_kcm bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.00% gnome-shell bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > 0.00% firefox bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.00% weechat bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.00% WebExtensions bpf_prog_c1bd85c092d6e4aa_sys_exit [k] bpf_prog_c1bd85c092d6e4aa_sys_exit > 0.00% Timer bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > 0.00% Web Content bpf_prog_819967866022f1e1_sys_enter [k] bpf_prog_819967866022f1e1_sys_enter > [root@quaco perf]# > > Ok, lets check that bpf_prog_819967866022f1e1_sys_enter symbol, 38% of > the samples at just at that %rbp, more in a previous run... > > [root@quaco perf]# perf annotate --stdio2 bpf_prog_819967866022f1e1_sys_enter > Samples: 25 of event 'cycles', 4000 Hz, Event count (approx.): 7248318, [percent: local period] > bpf_prog_819967866022f1e1_sys_enter() bpf_prog_819967866022f1e1_sys_enter > 38.00 push %rbp > > 2.72 mov %rsp,%rbp > sub $0x170,%rsp > 13.19 sub $0x28,%rbp > 3.30 mov %rbx,0x0(%rbp) > 20.33 mov %r13,0x8(%rbp) > mov %r14,0x10(%rbp) > mov %r15,0x18(%rbp) > xor %eax,%eax > mov %rax,0x20(%rbp) > mov %rdi,%rbx > 13.34 → callq *ffffffffd359487f > mov %eax,-0x148(%rbp) > > So I ended up trying with a event group to check what could be that: > > [root@quaco perf]# perf record -a -e '{cycles,instructions,cache-misses}' sleep 2s > [ perf record: Woken up 18 times to write data ] > [ perf record: Captured and wrote 6.619 MB perf.data (91964 samples) ] > [root@quaco perf]# perf annotate --stdio2 bpf_prog_819967866022f1e1_sys_enter > Samples: 314 of events 'anon group { cycles, instructions, cache-misses }', 4000 Hz, Event count (approx.): 118106063, [percent: local period] > bpf_prog_819967866022f1e1_sys_enter() bpf_prog_819967866022f1e1_sys_enter > 20.88 24.58 49.11 push %rbp > > 47.37 31.62 26.71 mov %rsp,%rbp > 1.16 0.00 0.00 sub $0x170,%rsp > sub $0x28,%rbp > 0.58 2.48 0.00 mov %rbx,0x0(%rbp) > 7.10 5.92 0.00 mov %r13,0x8(%rbp) > 0.51 0.96 7.96 mov %r14,0x10(%rbp) > 0.00 1.10 0.00 mov %r15,0x18(%rbp) > 0.58 0.00 0.00 xor %eax,%eax > mov %rax,0x20(%rbp) > 2.39 0.85 0.00 mov %rdi,%rbx > 0.58 1.96 0.00 → callq *ffffffffd359487f > mov %eax,-0x148(%rbp) > 2.88 0.89 3.50 mov %rbp,%rsi > add $0xfffffffffffffeb8,%rsi > > So seems ok? I.e. that big cost at right the start of the BPF program is > just cache pressure, probably, right? > > > [root@quaco perf]# perf record -a -e '{L1-icache-load-misses,L1-dcache-load-misses}' sleep 2s > [ perf record: Woken up 14 times to write data ] > [ perf record: Captured and wrote 5.557 MB perf.data (72026 samples) ] > [root@quaco perf]# perf annotate --stdio2 bpf_prog_819967866022f1e1_sys_enter > Samples: 376 of events 'anon group { L1-icache-load-misses, L1-dcache-load-misses }', 4000 Hz, Event count (approx.): 3715276, [percent: local p> > bpf_prog_819967866022f1e1_sys_enter() bpf_prog_819967866022f1e1_sys_enter > 1.54 63.01 push %rbp > > 53.09 28.13 mov %rsp,%rbp > 0.58 0.00 sub $0x170,%rsp > 0.00 0.55 sub $0x28,%rbp > 6.96 0.00 mov %rbx,0x0(%rbp) > 10.25 0.00 mov %r13,0x8(%rbp) > 0.73 0.00 mov %r14,0x10(%rbp) > 3.04 0.00 mov %r15,0x18(%rbp) > > Looks like. furthermore: > > [root@quaco perf]# perf record -a -e '{L1-icache-load-misses,L1-dcache-load-misses,dTLB-load-misses,iTLB-load-misses}' sleep 2s > [ perf record: Woken up 21 times to write data ] > [ perf record: Captured and wrote 7.708 MB perf.data (112323 samples) ] > [root@quaco perf]# perf annotate --stdio2 bpf_prog_819967866022f1e1_sys_enter > Samples: 391 of events 'anon group { L1-icache-load-misses, L1-dcache-load-misses, dTLB-load-misses, iTLB-load-misses }', 4000 Hz, Event count (> > bpf_prog_819967866022f1e1_sys_enter() bpf_prog_819967866022f1e1_sys_enter > 1.98 64.42 100.00 13.66 push %rbp > > 50.79 23.91 0.00 82.23 mov %rsp,%rbp > sub $0x170,%rsp > 0.24 0.00 0.00 0.00 sub $0x28,%rbp > 7.73 0.00 0.00 0.00 mov %rbx,0x0(%rbp) > 11.13 0.44 0.00 0.00 mov %r13,0x8(%rbp) > mov %r14,0x10(%rbp) > 1.64 0.46 0.00 0.00 mov %r15,0x18(%rbp) > > Do these numbers look sane to you guys? >From my experiments, mov is often the top time consumer. But mov %rsp,%rbp is a little weird. It does not access cache, right? > > Song, I also noticed that source code is not being intermixed for the > --stdio annotation, while it works, to some degree, for '--tui', i.e. > when you do 'perf top', press '/bpf' to show just symbols with that > substring and then press enter or 'A' to annotate, we can see the > original C source code for the BPF program, but it is mangling the > screen sometimes, I need to try and fix, please take a look if you have > the time. I will take a look at this, most likely after LSFMM. > > Also things like the callq targets need some work to tell what function > is that, which as I said isn't appearing on the --stdio2 output, but > appears on the --tui, i.e. we need to resolve that symbol to check how > to map back to a BPF helper or any othe callq target. I am aware of missing callq symbol. I was thinking they are less critical with source code. > > Also, what about those 'je 0', i.e. the target is being misinterpreted > or is this some BPF construct I should've know about? :) I didn't notice the je 0 before. Let me try reproduce it. Thanks, Song > > 2.68 0.00 0.00 0.00 mov %rdi,%rbx > → callq *ffffffffd359487f > mov %eax,-0x148(%rbp) > 9.61 0.00 0.00 0.00 mov %rbp,%rsi > add $0xfffffffffffffeb8,%rsi > movabs $0xffff9d556c776c00,%rdi > > → callq *ffffffffd3595b2f > cmp $0x0,%rax > → je 0 > 0.00 1.25 0.00 0.00 add $0x38,%rax > 0.80 0.21 0.00 0.00 xor %r13d,%r13d > cmp $0x0,%rax > → jne 0 > mov %rbp,%rdi > add $0xfffffffffffffeb8,%rdi > > - Arnaldo
