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Date: Wed, 17 Sep 2014 13:55:08 -0400
From: Waiman Long <waiman.long@hp.com>
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To: Arnaldo Carvalho de Melo <acme@kernel.org>
CC: Peter Zijlstra <peterz@infradead.org>, Paul Mackerras <paulus@samba.org>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        Scott J Norton <scott.norton@hp.com>, Don Zickus <dzickus@redhat.com>,
        Jiri Olsa <jolsa@kernel.org>, Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH v2] perf mem: improves DSO long names search speed with
 RB tree
References: <1410894499-27609-1-git-send-email-Waiman.Long@hp.com> <1410894499-27609-2-git-send-email-Waiman.Long@hp.com> <20140917145102.GA2770@kernel.org>
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On 09/17/2014 10:51 AM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Sep 16, 2014 at 03:08:19PM -0400, Waiman Long escreveu:
>> +++ b/tools/perf/util/dso.c
>> @@ -611,17 +611,93 @@ struct dso *dso__kernel_findnew(struct machine *machine, const char *name,
>>   	return dso;
>>   }
>>
>> +/*
>> + * RB root of DSOs sorted by the long name
>> + */
>> +static struct rb_root dso__longname_root = { NULL };
> Use RB_ROOT, like in:
>
> [acme@zoo linux]$ grep -w rb_root mm/vmalloc.c
> static struct rb_root vmap_area_root = RB_ROOT;
> [acme@zoo linux]$

I don't use RB_ROOT here because it gave compilation error.

> But then can't this be made non-static, i.e. at the 'struct machine'
> level? I.e.  it is more likely that DSOs with the same long name are
> really the same thing on a single 'struct machine', not accross multiple
> ones or even multiple sessions (i.e. across multiple 'struct machines').
>
> IIRC Adrian also pointed this out.
>
> - Arnaldo
>
>

Yes, I am going to put the rb_root in the machine structure level as 
suggested by Adrian. So the static rb_root will be gone. I also found 
out that the dso__load_sym() function in util/symbol-elf.c may create 
DSOs of the same long name which can be either "[kernel.allsyms]" or 
"/lib/modules/.../vmlinux".

Cheers,
Longman