Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261369AbTH0SRq (ORCPT ); Wed, 27 Aug 2003 14:17:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261861AbTH0SRq (ORCPT ); Wed, 27 Aug 2003 14:17:46 -0400 Received: from meryl.it.uu.se ([130.238.12.42]:13214 "EHLO meryl.it.uu.se") by vger.kernel.org with ESMTP id S261369AbTH0SRk (ORCPT ); Wed, 27 Aug 2003 14:17:40 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16204.62914.298711.293389@gargle.gargle.HOWL> Date: Wed, 27 Aug 2003 20:17:38 +0200 From: Mikael Pettersson To: herbert@13thfloor.at Cc: linux-kernel@vger.kernel.org, Marcelo Tosatti Subject: Re: UP optimizations .. In-Reply-To: <20030827160315.GD26817@www.13thfloor.at> References: <20030827160315.GD26817@www.13thfloor.at> X-Mailer: VM 6.90 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5068 Lines: 179 Herbert =?iso-8859-1?Q?P=F6tzl?= writes: > > Hi Mikael! > Hi Marcelo! > > stumbled repeatedly over the patches (or what remained of them) > from Mikael?, replacing task->processor and friends by inline > functions task_cpu(task), to eliminate them on UP systems ... > > my questions: > - is there an up to date patchset? Yes, I've kept it up to date. In fact I've been using it in every single 2.4 kernel I've built for the last 18+ months. Lately also on ppc32 and x86-64. Below is the current UP micro-optimisation patch set for 2.4.22. It changes p->processor, p->cpus_allowed, and p->cpus_runnable accesses (reads and writes) to use inline functions. In UP kernels these reduce to doing nothing or returning a constant. To keep the patch small, it doesn't change accesses in SMP-only code. (This is also the reason why p->cpus_runnable only has a wrapper for updates, since all reads are in SMP-only code.) /Mikael diff -ruN linux-2.4.22/fs/proc/array.c linux-2.4.22.up-opt/fs/proc/array.c --- linux-2.4.22/fs/proc/array.c 2003-06-14 13:30:27.000000000 +0200 +++ linux-2.4.22.up-opt/fs/proc/array.c 2003-08-27 19:42:34.159566477 +0200 @@ -390,7 +390,7 @@ task->nswap, task->cnswap, task->exit_signal, - task->processor); + task_cpu(task)); if(mm) mmput(mm); return res; diff -ruN linux-2.4.22/include/linux/sched.h linux-2.4.22.up-opt/include/linux/sched.h --- linux-2.4.22/include/linux/sched.h 2003-06-14 13:30:29.000000000 +0200 +++ linux-2.4.22.up-opt/include/linux/sched.h 2003-08-27 19:42:34.161566172 +0200 @@ -559,17 +559,77 @@ return p; } +/* + * Wrappers for p->processor/cpus_allowed/cpus_runnable access. No-op on UP. + */ +#ifdef CONFIG_SMP + +static inline int task_cpu(const struct task_struct *p) +{ + return p->processor; +} + +static inline void set_task_cpu(struct task_struct *p, int cpu) +{ + p->processor = cpu; +} + +static inline unsigned long task_cpus_allowed(const struct task_struct *p) +{ + return p->cpus_allowed; +} + +static inline void set_task_cpus_allowed(struct task_struct *p, + unsigned long cpus_allowed) +{ + p->cpus_allowed = cpus_allowed; +} + +static inline void set_task_cpus_runnable(struct task_struct *p, + unsigned long cpus_runnable) +{ + p->cpus_runnable = cpus_runnable; +} + +#else + +static inline int task_cpu(const struct task_struct *p) +{ + return 0; +} + +static inline void set_task_cpu(struct task_struct *p, int cpu) +{ +} + +static inline unsigned long task_cpus_allowed(const struct task_struct *p) +{ + return ~0UL; +} + +static inline void set_task_cpus_allowed(struct task_struct *p, + unsigned long cpus_allowed) +{ +} + +static inline void set_task_cpus_runnable(struct task_struct *p, + unsigned long cpus_runnable) +{ +} + +#endif /* CONFIG_SMP */ + #define task_has_cpu(tsk) ((tsk)->cpus_runnable != ~0UL) static inline void task_set_cpu(struct task_struct *tsk, unsigned int cpu) { - tsk->processor = cpu; - tsk->cpus_runnable = 1UL << cpu; + set_task_cpu(tsk, cpu); + set_task_cpus_runnable(tsk, 1UL << cpu); } static inline void task_release_cpu(struct task_struct *tsk) { - tsk->cpus_runnable = ~0UL; + set_task_cpus_runnable(tsk, ~0UL); } /* per-UID process charging. */ diff -ruN linux-2.4.22/kernel/sched.c linux-2.4.22.up-opt/kernel/sched.c --- linux-2.4.22/kernel/sched.c 2003-08-25 20:07:50.000000000 +0200 +++ linux-2.4.22.up-opt/kernel/sched.c 2003-08-27 19:42:34.163565866 +0200 @@ -359,7 +359,7 @@ if (task_on_runqueue(p)) goto out; add_to_runqueue(p); - if (!synchronous || !(p->cpus_allowed & (1UL << smp_processor_id()))) + if (!synchronous || !(task_cpus_allowed(p) & (1UL << smp_processor_id()))) reschedule_idle(p); success = 1; out: @@ -557,7 +557,7 @@ BUG_ON(!current->active_mm); need_resched_back: prev = current; - this_cpu = prev->processor; + this_cpu = task_cpu(prev); if (unlikely(in_interrupt())) { printk("Scheduling in interrupt\n"); @@ -1364,7 +1364,7 @@ } sched_data->curr = current; sched_data->last_schedule = get_cycles(); - clear_bit(current->processor, &wait_init_idle); + clear_bit(task_cpu(current), &wait_init_idle); } extern void init_timervecs (void); @@ -1378,7 +1378,7 @@ int cpu = smp_processor_id(); int nr; - init_task.processor = cpu; + set_task_cpu(&init_task, cpu); for(nr = 0; nr < PIDHASH_SZ; nr++) pidhash[nr] = NULL; diff -ruN linux-2.4.22/kernel/softirq.c linux-2.4.22.up-opt/kernel/softirq.c --- linux-2.4.22/kernel/softirq.c 2002-11-30 17:12:32.000000000 +0100 +++ linux-2.4.22.up-opt/kernel/softirq.c 2003-08-27 19:42:34.164565713 +0200 @@ -368,7 +368,7 @@ sigfillset(¤t->blocked); /* Migrate to the right CPU */ - current->cpus_allowed = 1UL << cpu; + set_task_cpus_allowed(current, 1UL << cpu); while (smp_processor_id() != cpu) schedule(); - 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/