From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932675AbVLHWfX (ORCPT ); Thu, 8 Dec 2005 17:35:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932681AbVLHWfX (ORCPT ); Thu, 8 Dec 2005 17:35:23 -0500 Received: from uproxy.gmail.com ([66.249.92.196]:20082 "EHLO uproxy.gmail.com") by vger.kernel.org with ESMTP id S932675AbVLHWfW (ORCPT ); Thu, 8 Dec 2005 17:35:22 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:from:to:subject:date:user-agent:cc:mime-version:content-disposition:content-type:content-transfer-encoding:message-id; b=m4Cl6qHmkgKXOxBANCWLlseoOgS9WhLVZSXfbVRXAAP/EqdDkfcQ/Y6LE4pirccQF5OeQFs/kt9WGMqqrXN4r0AdoT9sPSUxjvv2mY3RDjb4zfgXg1rEZGVRHUB0FdsLHD+2YT08ToTGPYgON4/hVu0l5I9PNs48vam+ZrhWu9E= From: Jesper Juhl To: Linux Kernel Mailing List Subject: [PATCH] Decrease number of pointer derefs in exit.c Date: Thu, 8 Dec 2005 23:35:42 +0100 User-Agent: KMail/1.9 Cc: Linus Torvalds , Ingo Molnar , Andrew Morton , Jesper Juhl MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <200512082335.42811.jesper.juhl@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, Here's a small patch to decrease the number of pointer derefs in kernel/exit.c Benefits of the patch: - Fewer pointer dereferences should make the code slightly faster. - Size of generated code is smaller - improved readability Please consider applying. Signed-off-by: Jesper Juhl Acked-by: Ingo Molnar --- kernel/exit.c | 37 +++++++++++++++++++++---------------- 1 files changed, 21 insertions(+), 16 deletions(-) text data bss dec hex filename 11077 0 0 11077 2b45 exit.o.orig 10997 0 0 10997 2af5 exit.o --- linux-2.6.15-rc5-git1-orig/kernel/exit.c 2005-12-04 18:48:53.000000000 +0100 +++ linux-2.6.15-rc5-git1/kernel/exit.c 2005-12-06 22:11:17.000000000 +0100 @@ -1068,6 +1068,9 @@ static int wait_task_zombie(task_t *p, i } if (likely(p->real_parent == p->parent) && likely(p->signal)) { + struct signal_struct *psig; + struct signal_struct *sig; + /* * The resource counters for the group leader are in its * own task_struct. Those for dead threads in the group @@ -1084,24 +1087,26 @@ static int wait_task_zombie(task_t *p, i * here reaping other children at the same time. */ spin_lock_irq(&p->parent->sighand->siglock); - p->parent->signal->cutime = - cputime_add(p->parent->signal->cutime, + psig = p->parent->signal; + sig = p->signal; + psig->cutime = + cputime_add(psig->cutime, cputime_add(p->utime, - cputime_add(p->signal->utime, - p->signal->cutime))); - p->parent->signal->cstime = - cputime_add(p->parent->signal->cstime, + cputime_add(sig->utime, + sig->cutime))); + psig->cstime = + cputime_add(psig->cstime, cputime_add(p->stime, - cputime_add(p->signal->stime, - p->signal->cstime))); - p->parent->signal->cmin_flt += - p->min_flt + p->signal->min_flt + p->signal->cmin_flt; - p->parent->signal->cmaj_flt += - p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt; - p->parent->signal->cnvcsw += - p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw; - p->parent->signal->cnivcsw += - p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw; + cputime_add(sig->stime, + sig->cstime))); + psig->cmin_flt += + p->min_flt + sig->min_flt + sig->cmin_flt; + psig->cmaj_flt += + p->maj_flt + sig->maj_flt + sig->cmaj_flt; + psig->cnvcsw += + p->nvcsw + sig->nvcsw + sig->cnvcsw; + psig->cnivcsw += + p->nivcsw + sig->nivcsw + sig->cnivcsw; spin_unlock_irq(&p->parent->sighand->siglock); }