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    Subject[PATCH 02/14] perf tools: Cache register accesses for unwind processing
    Date
    Caching registers value into an array. Got about 4% speed up
    of perf_reg_value function for report command processing
    dwarf unwind stacks.

    Output from report over 1.5 GB data with DWARF unwind stacks:
    (TODO fix perf diff)

    current code:
    5.84% perf perf [.] perf_reg_value
    change:
    1.94% perf perf [.] perf_reg_value

    And little bit of overall speed up:
    (perf stat -r 5 -e '{cycles,instructions}:u' ...)

    current code:
    310,298,611,754 cycles ( +- 0.33% )
    439,669,689,341 instructions ( +- 0.03% )

    188.656753166 seconds time elapsed ( +- 0.82% )

    change:
    291,315,329,878 cycles ( +- 0.22% )
    391,763,485,304 instructions ( +- 0.03% )

    180.742249687 seconds time elapsed ( +- 0.64% )

    Acked-by: Namhyung Kim <namhyung@kernel.org>
    Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
    Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Jean Pihet <jean.pihet@linaro.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/1401892622-30848-2-git-send-email-jolsa@kernel.org
    Signed-off-by: Jiri Olsa <jolsa@kernel.org>
    ---
    tools/perf/util/event.h | 5 +++++
    tools/perf/util/perf_regs.c | 10 +++++++++-
    tools/perf/util/perf_regs.h | 4 +++-
    3 files changed, 17 insertions(+), 2 deletions(-)

    diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
    index 9ba2eb3..e5dd40a 100644
    --- a/tools/perf/util/event.h
    +++ b/tools/perf/util/event.h
    @@ -7,6 +7,7 @@
    #include "../perf.h"
    #include "map.h"
    #include "build-id.h"
    +#include "perf_regs.h"

    struct mmap_event {
    struct perf_event_header header;
    @@ -89,6 +90,10 @@ struct regs_dump {
    u64 abi;
    u64 mask;
    u64 *regs;
    +
    + /* Cached values/mask filled by first register access. */
    + u64 cache_regs[PERF_REGS_MAX];
    + u64 cache_mask;
    };

    struct stack_dump {
    diff --git a/tools/perf/util/perf_regs.c b/tools/perf/util/perf_regs.c
    index a3539ef..43168fb 100644
    --- a/tools/perf/util/perf_regs.c
    +++ b/tools/perf/util/perf_regs.c
    @@ -1,11 +1,15 @@
    #include <errno.h>
    #include "perf_regs.h"
    +#include "event.h"

    int perf_reg_value(u64 *valp, struct regs_dump *regs, int id)
    {
    int i, idx = 0;
    u64 mask = regs->mask;

    + if (regs->cache_mask & (1 << id))
    + goto out;
    +
    if (!(mask & (1 << id)))
    return -EINVAL;

    @@ -14,6 +18,10 @@ int perf_reg_value(u64 *valp, struct regs_dump *regs, int id)
    idx++;
    }

    - *valp = regs->regs[idx];
    + regs->cache_mask |= (1 << id);
    + regs->cache_regs[id] = regs->regs[idx];
    +
    +out:
    + *valp = regs->cache_regs[id];
    return 0;
    }
    diff --git a/tools/perf/util/perf_regs.h b/tools/perf/util/perf_regs.h
    index 79c78f7..980dbf7 100644
    --- a/tools/perf/util/perf_regs.h
    +++ b/tools/perf/util/perf_regs.h
    @@ -2,7 +2,8 @@
    #define __PERF_REGS_H

    #include <linux/types.h>
    -#include "event.h"
    +
    +struct regs_dump;

    #ifdef HAVE_PERF_REGS_SUPPORT
    #include <perf_regs.h>
    @@ -11,6 +12,7 @@ int perf_reg_value(u64 *valp, struct regs_dump *regs, int id);

    #else
    #define PERF_REGS_MASK 0
    +#define PERF_REGS_MAX 0

    static inline const char *perf_reg_name(int id __maybe_unused)
    {
    --
    1.8.3.1


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