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Commit c6580451 authored by Jiri Olsa's avatar Jiri Olsa
Browse files

perf tools: Cache dso data file descriptor 



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: default avatarNamhyung 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: default avatarJiri Olsa <jolsa@kernel.org>
parent bda6ee4a

tools/perf/util/dso.c

+59 −2
Original line number Diff line number Diff line 
#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;

}

tools/perf/util/unwind-libunwind.c

+0 −2
Original line number Diff line number Diff line
@@ -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;