Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753459Ab3JLTGf (ORCPT ); Sat, 12 Oct 2013 15:06:35 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:53935 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753089Ab3JLTGd (ORCPT ); Sat, 12 Oct 2013 15:06:33 -0400 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Oleg Nesterov , Kosaki Motohiro , Andrew Morton Subject: [RFC PATCH 02/10] posix-timers: Remove dead process posix cpu timers caching Date: Sat, 12 Oct 2013 21:06:18 +0200 Message-Id: <1381604786-21293-3-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1381604786-21293-1-git-send-email-fweisbec@gmail.com> References: <1381604786-21293-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3163 Lines: 96 Now that we removed dead thread posix cpu timers caching, lets remove the dead process wide version. This caching is similar to the per thread version but it should be even more rare: * If the process id dead, we are not reading its timers status from a thread belonging to its group. So this only concern remote process timers reads. * Unlike per thread timers caching, this only applies to zombies targets. Buried targets process wide timers return 0 values. Then again this caching seem to complicate the code for corner cases that are probably not worth it. So lets get rid of it. Signed-off-by: Frederic Weisbecker Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Oleg Nesterov Cc: Kosaki Motohiro Cc: Andrew Morton --- kernel/posix-cpu-timers.c | 34 +--------------------------------- 1 file changed, 1 insertion(+), 33 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index b803265..dd75dc4 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -453,23 +453,6 @@ void posix_cpu_timers_exit_group(struct task_struct *tsk) tsk->se.sum_exec_runtime + sig->sum_sched_runtime); } -static void clear_dead_task(struct k_itimer *itimer, unsigned long long now) -{ - struct cpu_timer_list *timer = &itimer->it.cpu; - - /* - * That's all for this thread or process. - * We leave our residual in expires to be reported. - */ - put_task_struct(timer->task); - timer->task = NULL; - if (timer->expires < now) { - timer->expires = 0; - } else { - timer->expires -= now; - } -} - static inline int expires_gt(cputime_t expires, cputime_t new_exp) { return expires == 0 || expires > new_exp; @@ -831,16 +814,6 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) goto dead; } else { cpu_timer_sample_group(timer->it_clock, p, &now); - if (unlikely(p->exit_state) && thread_group_empty(p)) { - read_unlock(&tasklist_lock); - /* - * We've noticed that the thread is dead, but - * not yet reaped. Take this opportunity to - * drop our task ref. - */ - clear_dead_task(timer, now); - goto dead; - } } read_unlock(&tasklist_lock); } @@ -1090,13 +1063,8 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) timer->it.cpu.expires = 0; goto out_unlock; } else if (unlikely(p->exit_state) && thread_group_empty(p)) { - /* - * We've noticed that the thread is dead, but - * not yet reaped. Take this opportunity to - * drop our task ref. - */ + /* Optimizations: if the process is dying, no need to rearm */ cpu_timer_sample_group(timer->it_clock, p, &now); - clear_dead_task(timer, now); goto out_unlock; } spin_lock(&p->sighand->siglock); -- 1.8.3.1 -- 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/