[PATCH v2] malloc: move tcache_init out of hot tcache paths

[Cupertino Miranda]

Hi Wilco,

On 15-04-2025 16:32, Wilco Dijkstra wrote:
> Hi Cupertino,
> 
>> @@ -3433,6 +3434,8 @@ __libc_malloc (size_t bytes)
>>   
>>     if (tcache_available (tc_idx))
>>       return tag_new_usable (tcache_get (tc_idx));
>> +  else
>> +    MAYBE_INIT_TCACHE ();
>> #endif
>>   
>>     return __libc_malloc2 (bytes);
> 
> It still has this which slows down malloc by adding a call. There is another issue with
> moving tcache initialization earlier: malloc is initialized in __libc_malloc2, so tcache
> will now be initialized before it - however tcache assumes malloc has been initialized
> before it...
Right, I understand better now the benefits of the tailcall.
That move of the call from __libc_malloc2 to __libc_malloc is clearly 
wrong. Sorry for that.
> 
>> @@ -3474,8 +3477,6 @@ __libc_free (void *mem)
>>       }
>>     else
>>       {
>> -      MAYBE_INIT_TCACHE ();
>> -
> 
> On latest trunk this has now moved to _int_free_chunk. We could also remove the errno
> save/restore from tcache_init since it's only there because of the above line.
Ok, will update the patch! Thanks for the hint on the errno.

Cheers,
Cupertino