Skip to content

cloud-kernel
cloud-kernel

openanolis / cloud-kernel
接近 2 年 前同步成功

通知 170
Star 36
Fork 7
cloud-kernel
cloud-kernel
切换分支/标签
  1. 17 5月, 2016 2 次提交
  3. 12 5月, 2016 5 次提交
  5. 11 5月, 2016 7 次提交
  7. 10 5月, 2016 15 次提交
  9. 07 5月, 2016 9 次提交
  11. 06 5月, 2016 2 次提交
    • C
      perf callchain: Fix incorrect ordering of entries · 9919a65e
      由 Chris Phlipot 提交于 
      The existing implementation of thread__resolve_callchain, under certain
circumstances, can assemble callchain entries in the incorrect order.

The callchain entries are resolved incorrectly for a sample when all of
the following conditions are met:

1. callchain_param.order is set to ORDER_CALLER

2. thread__resolve_callchain_sample is able to resolve callchain entries
   for the sample.

3. unwind__get_entries is also able to resolve callchain entries for the
   sample.

The fix is accomplished by reversing the order in which
thread__resolve_callchain_sample and unwind__get_entries are called when
callchain_param.order is set to ORDER_CALLER.

Unwind specific code from thread__resolve_callchain is also moved into a
new static function to improve readability of the fix.

How to Reproduce the Existing Bug:

Modifying perf script to print call trees in the opposite order or
applying the remaining patches from this series and comparing the
results output from export-to-postgtresql.py are the easiest ways to see
the bug, however it can still be seen in current builds using perf
report.

Here is how i can reproduce the bug using perf report:

  # perf record --call-graph=dwarf stress -c 1 -t 5

when i run this command:

  # perf report --call-graph=flat,0,0,callee

This callchain, containing kernel (handle_irq_event, etc) and userspace
samples (__libc_start_main, etc) is contained in the output, which looks
correct (callee order):

                gen8_irq_handler
                handle_irq_event_percpu
                handle_irq_event
                handle_edge_irq
                handle_irq
                do_IRQ
                ret_from_intr
                __random
                rand
                0x558f2a04dded
                0x558f2a04c774
                __libc_start_main
                0x558f2a04dcd9

Now run this command using caller order:

  # perf report --call-graph=flat,0,0,caller

It is expected to see the exact reverse of the above when using caller
order (with "0x558f2a04dcd9" at the top and "gen8_irq_handler" at the
bottom) in the output, but it is nowhere to be found.

instead you see this:

                ret_from_intr
                do_IRQ
                handle_irq
                handle_edge_irq
                handle_irq_event
                handle_irq_event_percpu
                gen8_irq_handler
                0x558f2a04dcd9
                __libc_start_main
                0x558f2a04c774
                0x558f2a04dded
                rand
                __random

Notice how internally the kernel symbols are reversed and the user space
symbols are reversed, but the kernel symbols still appear above the user
space symbols.

if this patch is applied and perf script is re-run, you will see the
expected output (with "0x558f2a04dcd9" at the top and "gen8_irq_handler"
at the bottom):

                0x558f2a04dcd9
                __libc_start_main
                0x558f2a04c774
                0x558f2a04dded
                rand
                __random
                ret_from_intr
                do_IRQ
                handle_irq
                handle_edge_irq
                handle_irq_event
                handle_irq_event_percpu
                gen8_irq_handler
Signed-off-by: NChris Phlipot <cphlipot0@gmail.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1461831551-12213-2-git-send-email-cphlipot0@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      9919a65e
    • A
      perf trace: Do not print raw args list for syscalls with no args · 4c4d6e51
      由 Arnaldo Carvalho de Melo 提交于 
      The test to check if the arg format had been read from the
syscall:sys_enter_name/format file was looking at the list of non-commom
fields, and if that is empty, it would think it had failed to read it,
because it doesn't exist, for instance, for the clone() syscall.

So instead before dumping the raw syscall args list check
IS_ERR(sc->tp_format), if that is true, then an attempt was made to read
the format file and failed, in which case dump the raw arg list values.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ls7pmdqb2xy9339vdburwvnk@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      4c4d6e51