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perf tools: Cache dso data file descriptor

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Caching dso data file descriptors to avoid expensive re-opens
especially during DWARF unwind.

We keep dsos data file descriptors open until their count reaches
the half of the current fd open limit (RLIMIT_NOFILE). In this case
we close file descriptor of the first opened dso object.

We've got overall speedup (~27% for my workload) of report:
 'perf report --stdio -i perf-test.data' (3 runs)
  (perf-test.data size was around 12GB)

  current code:
   545,640,944,228      cycles                     ( +-  0.53% )
   785,255,798,320      instructions               ( +-  0.03% )

     366.340910010 seconds time elapsed            ( +-  3.65% )

  after change:
   435,895,036,114      cycles                     ( +-  0.26% )
   636,790,271,176      instructions               ( +-  0.04% )

     266.481463387 seconds time elapsed            ( +-  0.13% )

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/1401892622-30848-7-git-send-email-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
This commit is contained in:
Jiri Olsa 2014-04-30 15:47:27 +02:00
commit c658045197
2 changed files with 59 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

61
tools/perf/util/dso.c
View file

@ -1,4 +1,6 @@
#include <asm/bug.h>
#include <sys/time.h>
#include <sys/resource.h>
#include "symbol.h"
#include "dso.h"
#include "machine.h"
@ -180,12 +182,20 @@ static int __open_dso(struct dso *dso, struct machine *machine)
return fd;
}
static void check_data_close(void);
static int open_dso(struct dso *dso, struct machine *machine)
{
int fd = __open_dso(dso, machine);
if (fd > 0)
if (fd > 0) {
dso__list_add(dso);
/*
* Check if we crossed the allowed number
* of opened DSOs and close one if needed.
*/
check_data_close();
}
return fd;
}
@ -204,6 +214,54 @@ static void close_dso(struct dso *dso)
close_data_fd(dso);
}
static void close_first_dso(void)
{
struct dso *dso;
dso = list_first_entry(&dso__data_open, struct dso, data.open_entry);
close_dso(dso);
}
static rlim_t get_fd_limit(void)
{
struct rlimit l;
rlim_t limit = 0;
/* Allow half of the current open fd limit. */
if (getrlimit(RLIMIT_NOFILE, &l) == 0) {
if (l.rlim_cur == RLIM_INFINITY)
limit = l.rlim_cur;
else
limit = l.rlim_cur / 2;
} else {
pr_err("failed to get fd limit\n");
limit = 1;
}
return limit;
}
static bool may_cache_fd(void)
{
static rlim_t limit;
if (!limit)
limit = get_fd_limit();
if (limit == RLIM_INFINITY)
return true;
return limit > (rlim_t) dso__data_open_cnt;
}
static void check_data_close(void)
{
bool cache_fd = may_cache_fd();
if (!cache_fd)
close_first_dso();
}
void dso__data_close(struct dso *dso)
{
close_dso(dso);
@ -356,7 +414,6 @@ dso_cache__read(struct dso *dso, struct machine *machine,
if (ret <= 0)
free(cache);
dso__data_close(dso);
return ret;
}

2
tools/perf/util/unwind-libunwind.c
View file

@ -250,7 +250,6 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
/* Check the .eh_frame section for unwinding info */
offset = elf_section_offset(fd, ".eh_frame_hdr");
dso__data_close(dso);
if (offset)
ret = unwind_spec_ehframe(dso, machine, offset,
@ -271,7 +270,6 @@ static int read_unwind_spec_debug_frame(struct dso *dso,
/* Check the .debug_frame section for unwinding info */
*offset = elf_section_offset(fd, ".debug_frame");
dso__data_close(dso);
if (*offset)
return 0;