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SubjectRe: [PATCH 1/2] perf tools: avoid traverse dsos list while find vdso
Em Mon, Sep 09, 2013 at 09:21:55PM +0800, Chenggang Qin escreveu:
> From: Chenggang Qin <chenggang.qcg@taobao.com>
>
> Vdso is only one in a system. It is not necessory to traverse the
> macine->user_dsos list when looking for the dso of vdso.
> The flag vdso_found should be replaced by a pointor that point to the dso of
> vdso. If the pointer is NULL, dso of vdso have not been created. Else, the
> pointor can be returned directly in function vdso__dso_findnew().
> The list traversing can be avoided by this method.
> Thanks.
>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
> Cc: Arjan van de Ven <arjan@linux.intel.com>
> Cc: Namhyung Kim <namhyung@gmail.com>
> Cc: Yanmin Zhang <yanmin.zhang@intel.com>
> Cc: Wu Fengguang <fengguang.wu@intel.com>
> Cc: Mike Galbraith <efault@gmx.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Chenggang Qin <chenggang.qcg@taobao.com>
>
> ---
> tools/perf/util/vdso.c | 22 ++++++++--------------
> 1 files changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
> index 3915982..8022ef0 100644
> --- a/tools/perf/util/vdso.c
> +++ b/tools/perf/util/vdso.c
> @@ -13,7 +13,7 @@
> #include "symbol.h"
> #include "linux/string.h"
>
> -static bool vdso_found;
> +static struct dso *vdso_dso = NULL;
> static char vdso_file[] = "/tmp/perf-vdso.so-XXXXXX";
>
> static int find_vdso_map(void **start, void **end)
> @@ -55,9 +55,6 @@ static char *get_file(void)
> size_t size;
> int fd;
>
> - if (vdso_found)
> - return vdso_file;
> -
> if (find_vdso_map(&start, &end))
> return NULL;
>
> @@ -79,33 +76,30 @@ static char *get_file(void)
> out:
> free(buf);
>
> - vdso_found = (vdso != NULL);
> return vdso;
> }
>
> void vdso__exit(void)
> {
> - if (vdso_found)
> + if (vdso_dso)
> unlink(vdso_file);

Don't we have to delete the vfso_dso and set it to NULL?

> }
>
> struct dso *vdso__dso_findnew(struct list_head *head)
> {
> - struct dso *dso = dsos__find(head, VDSO__MAP_NAME, true);
> -
> - if (!dso) {
> + if (!vdso_dso) {
> char *file;
>
> file = get_file();
> if (!file)
> return NULL;
>
> - dso = dso__new(VDSO__MAP_NAME);
> - if (dso != NULL) {
> - dsos__add(head, dso);
> - dso__set_long_name(dso, file);
> + vdso_dso = dso__new(VDSO__MAP_NAME);
> + if (vdso_dso != NULL) {
> + dsos__add(head, vdso_dso);
> + dso__set_long_name(vdso_dso, file);
> }
> }
>
> - return dso;
> + return vdso_dso;
> }
> --
> 1.7.8.rc2.5.g815b


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