1. 15 May, 2018 1 commit
  2. 03 May, 2017 1 commit
  3. 15 Dec, 2016 1 commit
    • Joe Stringer's avatar
      samples/bpf: Make samples more libbpf-centric · d40fc181
      Joe Stringer authored
      Switch all of the sample code to use the function names from
      tools/lib/bpf so that they're consistent with that, and to declare their
      own log buffers. This allow the next commit to be purely devoted to
      getting rid of the duplicate library in samples/bpf.
      Committer notes:
      Testing it:
      On a fedora rawhide container, with clang/llvm 3.9, sharing the host
      linux kernel git tree:
        # make O=/tmp/build/linux/ headers_install
        # make O=/tmp/build/linux -C samples/bpf/
      Since I forgot to make it privileged, just tested it outside the
      container, using what it generated:
        # uname -a
        Linux jouet 4.9.0-rc8+ #1 SMP Mon Dec 12 11:20:49 BRT 2016 x86_64 x86_64 x86_64 GNU/Linux
        # cd /var/lib/docker/devicemapper/mnt/c43e09a53ff56c86a07baf79847f00e2cc2a17a1e2220e1adbf8cbc62734feda/rootfs/tmp/build/linux/samples/bpf/
        # ls -la offwaketime
        -rwxr-xr-x. 1 root root 24200 Dec 15 12:19 offwaketime
        # file offwaketime
        offwaketime: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=c940d3f127d5e66cdd680e42d885cb0b64f8a0e4, not stripped
        # readelf -SW offwaketime_kern.o  | grep PROGBITS
        [ 2] .text             PROGBITS        0000000000000000 000040 000000 00  AX  0   0  4
        [ 3] kprobe/try_to_wake_up PROGBITS        0000000000000000 000040 0000d8 00  AX  0   0  8
        [ 5] tracepoint/sched/sched_switch PROGBITS        0000000000000000 000118 000318 00  AX  0   0  8
        [ 7] maps              PROGBITS        0000000000000000 000430 000050 00  WA  0   0  4
        [ 8] license           PROGBITS        0000000000000000 000480 000004 00  WA  0   0  1
        [ 9] version           PROGBITS        0000000000000000 000484 000004 00  WA  0   0  4
        # ./offwaketime | head -5
        swapper/1;start_secondary;cpu_startup_entry;schedule_preempt_disabled;schedule;__schedule;-;---;; 106
        CPU 0/KVM;entry_SYSCALL_64_fastpath;sys_ioctl;do_vfs_ioctl;kvm_vcpu_ioctl;kvm_arch_vcpu_ioctl_run;kvm_vcpu_block;schedule;__schedule;-;try_to_wake_up;swake_up_locked;swake_up;apic_timer_expired;apic_timer_fn;__hrtimer_run_queues;hrtimer_interrupt;local_apic_timer_interrupt;smp_apic_timer_interrupt;__irqentry_text_start;cpuidle_enter;call_cpuidle;cpu_startup_entry;start_secondary;;swapper/3 2
        Compositor;entry_SYSCALL_64_fastpath;sys_futex;do_futex;futex_wait;futex_wait_queue_me;schedule;__schedule;-;try_to_wake_up;futex_requeue;do_futex;sys_futex;entry_SYSCALL_64_fastpath;;SoftwareVsyncTh 5
        firefox;entry_SYSCALL_64_fastpath;sys_poll;do_sys_poll;poll_schedule_timeout;schedule_hrtimeout_range;schedule_hrtimeout_range_clock;schedule;__schedule;-;try_to_wake_up;pollwake;__wake_up_common;__wake_up_sync_key;pipe_write;__vfs_write;vfs_write;sys_write;entry_SYSCALL_64_fastpath;;Timer 13
        JS Helper;entry_SYSCALL_64_fastpath;sys_futex;do_futex;futex_wait;futex_wait_queue_me;schedule;__schedule;-;try_to_wake_up;do_futex;sys_futex;entry_SYSCALL_64_fastpath;;firefox 2
      Signed-off-by: 's avatarJoe Stringer <joe@ovn.org>
      Tested-by: 's avatarArnaldo Carvalho de Melo <acme@redhat.com>
      Cc: Alexei Starovoitov <ast@fb.com>
      Cc: Daniel Borkmann <daniel@iogearbox.net>
      Cc: Wang Nan <wangnan0@huawei.com>
      Cc: netdev@vger.kernel.org
      Link: http://lkml.kernel.org/r/20161214224342.12858-2-joe@ovn.orgSigned-off-by: 's avatarArnaldo Carvalho de Melo <acme@redhat.com>
  4. 28 Nov, 2016 1 commit
    • Daniel Borkmann's avatar
      bpf: fix multiple issues in selftest suite and samples · e00c7b21
      Daniel Borkmann authored
      1) The test_lru_map and test_lru_dist fails building on my machine since
         the sys/resource.h header is not included.
      2) test_verifier fails in one test case where we try to call an invalid
         function, since the verifier log output changed wrt printing function
      3) Current selftest suite code relies on sysconf(_SC_NPROCESSORS_CONF) for
         retrieving the number of possible CPUs. This is broken at least in our
         scenario and really just doesn't work.
         glibc tries a number of things for retrieving _SC_NPROCESSORS_CONF.
         First it tries equivalent of /sys/devices/system/cpu/cpu[0-9]* | wc -l,
         if that fails, depending on the config, it either tries to count CPUs
         in /proc/cpuinfo, or returns the _SC_NPROCESSORS_ONLN value instead.
         If /proc/cpuinfo has some issue, it returns just 1 worst case. This
         oddity is nothing new [1], but semantics/behaviour seems to be settled.
         _SC_NPROCESSORS_ONLN will parse /sys/devices/system/cpu/online, if
         that fails it looks into /proc/stat for cpuX entries, and if also that
         fails for some reason, /proc/cpuinfo is consulted (and returning 1 if
         unlikely all breaks down).
         While that might match num_possible_cpus() from the kernel in some
         cases, it's really not guaranteed with CPU hotplugging, and can result
         in a buffer overflow since the array in user space could have too few
         number of slots, and on perpcu map lookup, the kernel will write beyond
         that memory of the value buffer.
         William Tu reported such mismatches:
           [...] The fact that sysconf(_SC_NPROCESSORS_CONF) != num_possible_cpu()
           happens when CPU hotadd is enabled. For example, in Fusion when
           setting vcpu.hotadd = "TRUE" or in KVM, setting ./qemu-system-x86_64
           -smp 2, maxcpus=4 ... the num_possible_cpu() will be 4 and sysconf()
           will be 2 [2]. [...]
         Documentation/cputopology.txt says /sys/devices/system/cpu/possible
         outputs cpu_possible_mask. That is the same as in num_possible_cpus(),
         so first step would be to fix the _SC_NPROCESSORS_CONF calls with our
         own implementation. Later, we could add support to bpf(2) for passing
         a mask via CPU_SET(3), for example, to just select a subset of CPUs.
         BPF samples code needs this fix as well (at least so that people stop
         copying this). Thus, define bpf_num_possible_cpus() once in selftests
         and import it from there for the sample code to avoid duplicating it.
         The remaining sysconf(_SC_NPROCESSORS_CONF) in samples are unrelated.
      After all three issues are fixed, the test suite runs fine again:
        # make run_tests | grep self
        selftests: test_verifier [PASS]
        selftests: test_maps [PASS]
        selftests: test_lru_map [PASS]
        selftests: test_kmod.sh [PASS]
        [1] https://www.sourceware.org/ml/libc-alpha/2011-06/msg00079.html
        [2] https://www.mail-archive.com/netdev@vger.kernel.org/msg121183.html
      Fixes: 3059303f ("samples/bpf: update tracex[23] examples to use per-cpu maps")
      Fixes: 86af8b41 ("Add sample for adding simple drop program to link")
      Fixes: df570f57 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_ARRAY")
      Fixes: e1559671 ("samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_HASH")
      Fixes: ebb676da ("bpf: Print function name in addition to function id")
      Fixes: 5db58faf ("bpf: Add tests for the LRU bpf_htab")
      Signed-off-by: 's avatarDaniel Borkmann <daniel@iogearbox.net>
      Cc: William Tu <u9012063@gmail.com>
      Acked-by: 's avatarAlexei Starovoitov <ast@kernel.org>
      Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
  5. 06 Feb, 2016 1 commit
  6. 02 Apr, 2015 1 commit
    • Alexei Starovoitov's avatar
      samples/bpf: Add IO latency analysis (iosnoop/heatmap) tool · 5c7fc2d2
      Alexei Starovoitov authored
      BPF C program attaches to
      blk_mq_start_request()/blk_update_request() kprobe events to
      calculate IO latency.
      For every completed block IO event it computes the time delta
      in nsec and records in a histogram map:
      User space reads this histogram map every 2 seconds and prints
      it as a 'heatmap' using gray shades of text terminal. Black
      spaces have many events and white spaces have very few events.
      Left most space is the smallest latency, right most space is
      the largest latency in the range.
      	$ sudo ./tracex3
      	and do 'sudo dd if=/dev/sda of=/dev/null' in other terminal.
      Observe IO latencies and how different activity (like 'make
      kernel') affects it.
      Similar experiments can be done for network transmit latencies,
      syscalls, etc.
      '-t' flag prints the heatmap using normal ascii characters:
      $ sudo ./tracex3 -t
        heatmap of IO latency
        # - many events with this latency
          - few events
      	|1us      |10us     |100us    |1ms      |10ms     |100ms    |1s |10s
      				 *ooo. *O.#.                                    # 221
      			      .  *#     .                                       # 125
      				 ..   .o#*..                                    # 55
      			    .  . .  .  .#O                                      # 37
      				 .#                                             # 175
      				       .#*.                                     # 37
      				  #                                             # 199
      		      .              . *#*.                                     # 55
      				       *#..*                                    # 42
      				  #                                             # 266
      			      ...***Oo#*OO**o#* .                               # 629
      				  #                                             # 271
      				      . .#o* o.*o*                              # 221
      				. . o* *#O..                                    # 50
      Signed-off-by: 's avatarAlexei Starovoitov <ast@plumgrid.com>
      Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
      Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
      Cc: Daniel Borkmann <daniel@iogearbox.net>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Jiri Olsa <jolsa@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Link: http://lkml.kernel.org/r/1427312966-8434-9-git-send-email-ast@plumgrid.comSigned-off-by: 's avatarIngo Molnar <mingo@kernel.org>