Messages in this thread | | | From | Frederic Weisbecker <> | Subject | [RFC][PATCH 0/5] hw-breakpoints: Make the API generic + support for perfcounters | Date | Mon, 20 Jul 2009 13:08:02 -0400 |
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Hi,
This patchset aims to make the hardware breakpoint API generic and also to provide the support for hardware breakpoints from perfcounters.
The hardware breakpoint API changes are a first shot of idea.
The support for perf counter has strange effects. It looks like only a part of the breakpoint events are actually recorded. The triggered callback receives well the events but if there are only few of them, none is passed in userspace (or userspace ignores them, dunno). Once I have some time, I'll take a deeper look inside the perf mmap syscall or whatever could be the origin.
Thanks.
Example which traces the BKL accesses by stressing reiserfs:
bkl=0x$(cat ../../System.map | grep kernel_flag | cut -d" " -f 1) ./perf record -f -g -e 5:$bkl -- dbench -t 20 20 ./perf report -g -s s # Samples: 36 # # Overhead Symbol # ........ ...... # 83.33% [k] lock_kernel | |--51.72%-- __pwrite64 | |--27.59%-- 0x7f9d83a17b15 | |--13.79%-- __open | --10.34%-- unlink
16.67% [k] unlock_kernel | |--80.00%-- 0x7f9d83a17b15 | |--20.00%-- unlink | --20.00%-- __pwrite64
Frederic Weisbecker (5): hw-breakpoints: Make kernel breakpoints API truly generic hw-breakpoints: Pull up the target symbol in a generic field hw-breakpoints: Make user breakpoints API truly generic perfcounter: Grow the event number to 64 bits perfcounter: Add support for kernel hardware breakpoints
arch/x86/include/asm/hw_breakpoint.h | 9 ++- arch/x86/kernel/hw_breakpoint.c | 91 +++++++++++----- arch/x86/kernel/ptrace.c | 21 ++-- include/asm-generic/hw_breakpoint.h | 116 ++++++++------------- include/linux/perf_counter.h | 1 + kernel/hw_breakpoint.c | 173 ++++++++++++++++++++++++++++--- kernel/perf_counter.c | 41 +++++++- kernel/trace/trace.h | 5 +- kernel/trace/trace_ksym.c | 67 ++++++------ kernel/trace/trace_selftest.c | 2 +- samples/hw_breakpoint/data_breakpoint.c | 10 +-- 11 files changed, 368 insertions(+), 168 deletions(-)
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