Re: [PATCH v4 2/2] perf tool: improves DSO long names lookup speed with rbtree

[Waiman Long]

On 09/29/2014 12:02 AM, Namhyung Kim wrote:
> On Fri, 26 Sep 2014 11:22:34 -0300, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Sep 24, 2014 at 11:45:40AM -0400, Waiman Long escreveu:
> > > +	/*
> > > +	 * Find node with the matching name
> > > +	 */
> > > +	while (*p) {
> > > +		struct dso *this = rb_entry(*p, struct dso, rb_node);
> > > +		long rc = (long)strcmp(name, this->long_name);
> > > +
> > > +		parent = *p;
> > > +		if (rc == 0) {
> > > +			/*
> > > +			 * In case the new DSO is a duplicate of an existing
> > > +			 * one, print an one-time warning&  sort the entry
> > > +			 * by its DSO address.
> > > +			 */
> > > +			if (!dso || (dso == this))
> > > +				return this;	/* Find matching dso */
> > > +			/*
> > > +			 * The kernel DSOs may have duplicated long name,
> > > +			 * so don't print warning for them.
> > > +			 */
> > > +			if (!warned&&  !strstr(name, "kernel.kallsyms")
> > > +				&&  !strstr(name, "/vmlinux")) {
> > > +				pr_warning("Duplicated dso long name: %s\n",
> > > +					   name);
> > Huh? Can you elaborate on this? Ho can we add multiple DSOs with the
> > exact same name into this tree? Have you actually seen this in practice?
> > I guess so, judging by the comment above ("may have").
> I guess it's because we split maps and dsos by section name (for kernel
> only).  Please look at dso__load_sym() - If map_groups__find_by_name()
> with short name + section name fails, it creates a new dso and map, and
> then curr_dso->long_name will be set as dso->long_name.
>
> Thanks,
> Namhyung

Yes, it is where I found that the different DSOs may have the same long 
name.

-Longman
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