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SubjectRe: [PATCH] perf util: optimize util/machine.c:machines__find().
On 11/21/13, 2:31 PM, Dongsheng Yang wrote:
> * Remove an unnecessary variable default_machine.
> * Return earlier to avoid unnecessary searching in children.
>
> Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
> ---
> tools/perf/util/machine.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 84cdb07..f0dd5f6 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -175,8 +175,7 @@ struct machine *machines__find(struct machines *machines, pid_t pid)
> {
> struct rb_node **p = &machines->guests.rb_node;
> struct rb_node *parent = NULL;
> - struct machine *machine;
> - struct machine *default_machine = NULL;
> + struct machine *machine = NULL;
>
> if (pid == HOST_KERNEL_ID)
> return &machines->host;
> @@ -184,17 +183,17 @@ struct machine *machines__find(struct machines *machines, pid_t pid)
> while (*p != NULL) {
> parent = *p;
> machine = rb_entry(parent, struct machine, rb_node);
> + if (!machine->pid)
> + break;
> if (pid < machine->pid)
> p = &(*p)->rb_left;
> else if (pid > machine->pid)
> p = &(*p)->rb_right;
> else
> - return machine;
> - if (!machine->pid)
> - default_machine = machine;
> + break;
> }
>
> - return default_machine;
> + return machine;
> }

This changes machines__find to always return the machine for the host
(pid == 0). This function is also used for VM lookups.

David



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