Re: [PATCH] de_thread: Use tsk not current.

From: Nick Piggin
Date: Tue Jul 11 2006 - 15:29:40 EST


Andrew Morton wrote:
On Mon, 10 Jul 2006 22:42:25 -0600
ebiederm@xxxxxxxxxxxx (Eric W. Biederman) wrote:


Ingo Oeser pointed out that because current expands to an inline function it
is more space efficient and somewhat faster to simply keep a cached copy of
current in another variable. This patch implements that for the de_thread
function.

- if (thread_group_empty(current))
+ if (thread_group_empty(tsk))
- if (unlikely(current->group_leader == child_reaper))
- child_reaper = current;
+ if (unlikely(tsk->group_leader == child_reaper))
+ child_reaper = tsk;
- zap_other_threads(current);
+ zap_other_threads(tsk);
read_unlock(&tasklist_lock);
...


This saves nearly 100 bytes of text on gcc-4.1.0/i686.

Why can't current be a pure function, I wonder?

--
SUSE Labs, Novell Inc.
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