[Mesa-dev] [PATCH 2/2] gallium/util: libunwind support

[Rob Clark]

On Tue, Apr 4, 2017 at 10:28 AM, Thomas Hellstrom <thellstrom at vmware.com> wrote:
> On 04/04/2017 04:06 PM, Rob Clark wrote:
>> On Tue, Apr 4, 2017 at 10:00 AM, Rob Clark <robdclark at gmail.com> wrote:
>>> On Tue, Apr 4, 2017 at 8:45 AM, Thomas Hellstrom <thellstrom at vmware.com> wrote:
>>>> On 04/04/2017 02:34 PM, Rob Clark wrote:
>>>>> On Tue, Apr 4, 2017 at 1:49 AM, Thomas Hellstrom <thellstrom at vmware.com> wrote:
>>>>>> But one more worrying thing is that with these fixes, debug_flush gets
>>>>>> too slow to be usable. I get about one frame every 5 seconds from Ubuntu
>>>>>> compiz. The culprit seems to be unw_get_proc_name(). Is there a way we
>>>>>> can save intermediate information during backtrace capture and call this
>>>>>> function at printout time?
>>>>> btw, is it common to capture many more backtraces than you print?
>>>>> (Just to check if defering the unw_get_proc_name() would actually help
>>>>> anything..)
>>>> Yes. The debug_flush functionality captures the backtrace on each map in
>>>> case someone would flush when mapped or try a recursive map. Only then
>>>> they are printed.
>>>>
>>>> FWIW in u_debug_symbol.c, José has implemented a hash table for name
>>>> lookups. Perhaps one solution would to save the IP and insert the
>>>> function name in the hash table with the IP as key.
>>>>
>>> fwiw, I added a hash-table:
>>>
>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_freedreno_mesa_commits_wip-2Dlibunwind&d=DwIFaQ&c=uilaK90D4TOVoH58JNXRgQ&r=wnSlgOCqfpNS4d02vP68_E9q2BNMCwfD2OZ_6dCFVQQ&m=VIINenNexQBSdAAjE5gNpegAuq9f_KOvkScYgqyZchQ&s=imNnOqL2QvjC7ok9q_QrCXSDr6AXpVgK4MYos9ZcyoM&e=
>>>
>>> It seems to work, but my hacked up test doesn't collect more
>>> stacktraces than it prints so haven't really tested it from
>>> performance standpoint.
>>>
>>> Possibly it could re-use debug_symbol_name_cached() instead, or at
>>> least not duplicate the hashtable..
>>>
>
> So, with your patches including the hash table, I'm up to speed again.
> But addr2line.sh doesn't work.
>

Do you have an example of a stacktrace before addr2line.sh?  I'm
trying to figure out the regexp's in that script but I guess it would
be easier if I knew what it was matching against.

BR,
-R