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

[Wilco Dijkstra]

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...

> @@ -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.

Cheers,
Wilco