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    SubjectRe: [PATCH 1/3] perf tools: Cache register accesses for unwind processing
    On 17/04/14 19:39, Jiri Olsa wrote:
    > 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:
    > 6.81% perf.old perf.old [.] perf_reg_value
    >
    > change:
    > 2.24% perf perf [.] perf_reg_value
    >
    > And little bit of speed up:
    >
    > Performance counter stats for './perf.old report -i perf-test.data --stdio':
    >
    > 134,664,011,577 cycles:u # 2.472 GHz
    > 189,677,227,475 instructions:u # 1.41 insns per cycle
    > 54465.096050 task-clock (msec) # 0.998 CPUs utilized
    >
    > 54.598339009 seconds time elapsed
    >
    > Performance counter stats for './perf report -i perf-test.data --stdio':
    >
    > 124,478,681,672 cycles:u # 2.466 GHz
    > 168,998,379,866 instructions:u # 1.36 insns per cycle
    > 50487.110482 task-clock (msec) # 0.997 CPUs utilized
    >
    > 50.635824229 seconds time elapsed
    >
    > 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: Namhyung Kim <namhyung@kernel.org>
    > Cc: Paul Mackerras <paulus@samba.org>
    > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
    > Cc: Jean Pihet <jean.pihet@linaro.org>
    > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
    > ---
    > 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 38457d4..970d4eb 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;
    > @@ -87,6 +88,10 @@ 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 d6e8b6a..80d8ab1 100644
    > --- a/tools/perf/util/perf_regs.h
    > +++ b/tools/perf/util/perf_regs.h
    > @@ -2,15 +2,17 @@
    > #define __PERF_REGS_H
    >
    > #include "types.h"
    > -#include "event.h"
    >
    > #ifdef HAVE_PERF_REGS_SUPPORT
    > #include <perf_regs.h>
    >
    > +struct regs_dump;
    > +
    > 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)
    > {
    >

    Want such a speedup,
    but it does not compile on my s390x system:

    CC util/top.o
    In file included from util/event.h:10:0,
    from util/event.c:2:
    util/perf_regs.h:24:6: error: ‘struct regs_dump’ declared inside parameter list [-Werror]
    util/perf_regs.h:24:6: error: its scope is only this definition or declaration, which is probably not what you want [-Werror]
    In file included from util/event.h:10:0,
    from util/callchain.h:7,
    from util/hist.h:6,
    from util/evsel.h:11,
    from util/evsel.c:18:
    util/perf_regs.h:24:6: error: ‘struct regs_dump’ declared inside parameter list [-Werror]
    util/perf_regs.h:24:6: error: its scope is only this definition or declaration, which is probably not what you want [-Werror]
    In file included from /home/cborntra/REPOS/linux/tools/perf/util/event.h:10:0,
    from /home/cborntra/REPOS/linux/tools/perf/util/debug.h:6,
    from util/cpumap.h:8,
    from util/top.c:9:
    /home/cborntra/REPOS/linux/tools/perf/util/perf_regs.h:24:6: error: ‘struct regs_dump’ declared inside parameter list [-Werror]
    /home/cborntra/REPOS/linux/tools/perf/util/perf_regs.h:24:6: error: its scope is only this definition or declaration, which is probably not what you want [-Werror]
    In file included from /home/cborntra/REPOS/linux/tools/perf/util/event.h:10:0,
    from /home/cborntra/REPOS/linux/tools/perf/util/debug.h:6,
    from util/cpumap.h:8,
    from util/evlist.c:12:
    /home/cborntra/REPOS/linux/tools/perf/util/perf_regs.h:24:6: error: ‘struct regs_dump’ declared inside parameter list [-Werror]
    /home/cborntra/REPOS/linux/tools/perf/util/perf_regs.h:24:6: error: its scope is only this definition or declaration, which is probably not what you want [-Werror]
    CC util/usage.o
    CC util/wrapper.o
    CC util/sigchain.o
    In file included from util/event.h:10:0,
    from util/header.h:8,
    from util/parse-options.c:4:
    util/perf_regs.h:24:6: error: ‘struct regs_dump’ declared inside parameter list [-Werror]
    util/perf_regs.h:24:6: error: its scope is only this definition or declaration, which is probably not what you want [-Werror]
    cc1: all warnings being treated as errors
    make[1]: *** [util/parse-options.o] Error 1
    make[1]: *** Waiting for unfinished jobs....
    cc1: all warnings being treated as errors
    cc1: all warnings being treated as errors
    make[1]: *** [util/event.o] Error 1
    make[1]: *** [util/evsel.o] Error 1
    In file included from util/event.h:10:0,
    from util/debug.h:6,
    from util/usage.c:10:
    util/perf_regs.h:24:6: error: ‘struct regs_dump’ declared inside parameter list [-Werror]
    util/perf_regs.h:24:6: error: its scope is only this definition or declaration, which is probably not what you want [-Werror]
    cc1: all warnings being treated as errors
    make[1]: *** [util/usage.o] Error 1
    cc1: all warnings being treated as errors
    make[1]: *** [util/evlist.o] Error 1
    cc1: all warnings being treated as errors
    make[1]: *** [util/top.o] Error 1


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