Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758274AbYFYOhj (ORCPT ); Wed, 25 Jun 2008 10:37:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756778AbYFYOgV (ORCPT ); Wed, 25 Jun 2008 10:36:21 -0400 Received: from mx1.redhat.com ([66.187.233.31]:51132 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753821AbYFYOgR (ORCPT ); Wed, 25 Jun 2008 10:36:17 -0400 Date: Wed, 25 Jun 2008 10:36:13 -0400 (EDT) From: Mikulas Patocka To: Denys Vlasenko cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, davem@davemloft.net Subject: Re: [3/10 PATCH] inline wake_up_bit In-Reply-To: <200806251617.40871.vda.linux@googlemail.com> Message-ID: References: <200806251617.40871.vda.linux@googlemail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2297 Lines: 61 On Wed, 25 Jun 2008, Denys Vlasenko wrote: > On Tuesday 24 June 2008 07:57, Mikulas Patocka wrote: >> Inline wake_up_bit. The function just pases arguments around. >> >> Signed-off-by: Mikulas Patocka >> >> int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned); >> -void wake_up_bit(void *, int); >> int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned); > >> +static __always_inline void wake_up_bit(void *word, int bit) >> +{ >> + __wake_up_bit(bit_waitqueue(word, bit), word, bit); >> +} > > So now every call to wake_up_bit(word, bit) now is converted to: > > __wake_up_bit(bit_waitqueue(word, bit), word, bit); > > which is in turn converted to (looking into your next patch): > > { > wait_queue_head_t *wq = bit_waitqueue(word, bit); > struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit); > if (waitqueue_active(wq)) > __wake_up(wq, TASK_NORMAL, 1, &key); > } > > which is in turn converted to (looking into your other patch): > > { > wait_queue_head_t *wq = bit_waitqueue(word, bit); > struct wait_bit_key key = __WAIT_BIT_KEY_INITIALIZER(word, bit); > if (waitqueue_active(wq)) > { > unsigned long flags; > spin_lock_irqsave(&qw->lock, flags); > __wake_up_common(wq, TASK_NORMAL, 1, 0, &key); > spin_unlock_irqrestore(&wq->lock, flags); > } > } > > And you know what? This is likely not the end yet! It's possible > spin_lock_irqXXX, __wake_up_common, waitqueue_active or bit_waitqueue > are inlines - I didn't check. > -- > vda Yes, that's 0.2% code size increase (or none increase, if drop inline-__wake_up_bit.patch and apply only the other patches). To me it seems crazy, how this code was refactored again and again over time, up to 8 levels of functions (including passing a pointer to a method). In 2.0.x kernel series, it was just a single call to wake up a queue. Mikulas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/