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    SubjectRe: [PATCH V2 1/7] trace/events: Add gup trace events
    On 12/2/2015 8:07 PM, Steven Rostedt wrote:
    > On Wed, 2 Dec 2015 14:53:27 -0800
    > Yang Shi <yang.shi@linaro.org> wrote:
    >
    >> page-faults events record the invoke to handle_mm_fault, but the invoke
    >> may come from do_page_fault or gup. In some use cases, the finer event count
    >> mey be needed, so add trace events support for:
    >>
    >> __get_user_pages
    >> __get_user_pages_fast
    >> fixup_user_fault
    >>
    >> Signed-off-by: Yang Shi <yang.shi@linaro.org>
    >> ---
    >> include/trace/events/gup.h | 71 ++++++++++++++++++++++++++++++++++++++++++++++
    >> 1 file changed, 71 insertions(+)
    >> create mode 100644 include/trace/events/gup.h
    >>
    >> diff --git a/include/trace/events/gup.h b/include/trace/events/gup.h
    >> new file mode 100644
    >> index 0000000..03a4674
    >> --- /dev/null
    >> +++ b/include/trace/events/gup.h
    >> @@ -0,0 +1,71 @@
    >> +#undef TRACE_SYSTEM
    >> +#define TRACE_SYSTEM gup
    >> +
    >> +#if !defined(_TRACE_GUP_H) || defined(TRACE_HEADER_MULTI_READ)
    >> +#define _TRACE_GUP_H
    >> +
    >> +#include <linux/types.h>
    >> +#include <linux/tracepoint.h>
    >> +
    >> +TRACE_EVENT(gup_fixup_user_fault,
    >> +
    >> + TP_PROTO(struct task_struct *tsk, struct mm_struct *mm,
    >> + unsigned long address, unsigned int fault_flags),
    >> +
    >> + TP_ARGS(tsk, mm, address, fault_flags),
    >
    > Arges added and not used by TP_fast_assign(), this will slow down the
    > code while tracing is enabled, as they need to be added to the trace
    > function call.
    >
    >> +
    >> + TP_STRUCT__entry(
    >> + __field( unsigned long, address )
    >> + ),
    >> +
    >> + TP_fast_assign(
    >> + __entry->address = address;
    >> + ),
    >> +
    >> + TP_printk("address=%lx", __entry->address)
    >> +);
    >> +
    >> +TRACE_EVENT(gup_get_user_pages,
    >> +
    >> + TP_PROTO(struct task_struct *tsk, struct mm_struct *mm,
    >> + unsigned long start, unsigned long nr_pages),
    >> +
    >> + TP_ARGS(tsk, mm, start, nr_pages),
    >
    > Here too but this is worse. See below.
    >
    >> +
    >> + TP_STRUCT__entry(
    >> + __field( unsigned long, start )
    >> + __field( unsigned long, nr_pages )
    >> + ),
    >> +
    >> + TP_fast_assign(
    >> + __entry->start = start;
    >> + __entry->nr_pages = nr_pages;
    >> + ),
    >> +
    >> + TP_printk("start=%lx nr_pages=%lu", __entry->start, __entry->nr_pages)
    >> +);
    >> +
    >> +TRACE_EVENT(gup_get_user_pages_fast,
    >> +
    >> + TP_PROTO(unsigned long start, int nr_pages, int write,
    >> + struct page **pages),
    >> +
    >> + TP_ARGS(start, nr_pages, write, pages),
    >
    > This and the above "gup_get_user_pages" have the same entry field,
    > assign and printk. They should be combined into a DECLARE_EVENT_CLASS()
    > and two DEFINE_EVENT()s. That will save on size as the
    > DECLARE_EVENT_CLASS() is the biggest part of each TRACE_EVENT().

    Thanks for the suggestion, will fix them in V3.

    Regards,
    Yang

    >
    > -- Steve
    >
    >
    >> +
    >> + TP_STRUCT__entry(
    >> + __field( unsigned long, start )
    >> + __field( unsigned long, nr_pages )
    >> + ),
    >> +
    >> + TP_fast_assign(
    >> + __entry->start = start;
    >> + __entry->nr_pages = nr_pages;
    >> + ),
    >> +
    >> + TP_printk("start=%lx nr_pages=%lu", __entry->start, __entry->nr_pages)
    >> +);
    >> +
    >> +#endif /* _TRACE_GUP_H */
    >> +
    >> +/* This part must be outside protection */
    >> +#include <trace/define_trace.h>
    >



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