Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755032Ab0HHWqJ (ORCPT ); Sun, 8 Aug 2010 18:46:09 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:60066 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751569Ab0HHWqH (ORCPT ); Sun, 8 Aug 2010 18:46:07 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=HAMdKMevuS/4eRxhM6kxDqdFWGut2jQpyJuyZYopNRNxruJY9VYYC2fJ8kDgVevryD vBApZenPxghb7s5Ca0zX70lh1b/fftq9MufjtO3LkWYS7rVyDpUeJRIcJDIBOG0nqXRi qoAG0YmHyraVSdWuAhNgMZcBpJIfDqG6OKzUY= From: Shawn Bohrer To: Alexander Viro Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Shawn Bohrer Subject: [PATCH] hrtimer: make epoll_wait() use the hrtimer range feature Date: Sun, 8 Aug 2010 17:45:32 -0500 Message-Id: <1281307532-3235-1-git-send-email-shawn.bohrer@gmail.com> X-Mailer: git-send-email 1.7.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3815 Lines: 122 This make epoll use hrtimers for the timeout value which prevents epoll_wait() from timing out up to a millisecond early. This mirrors the behavior of select() and poll(). Signed-off-by: Shawn Bohrer --- fs/eventpoll.c | 35 +++++++++++++++++++---------------- fs/select.c | 2 +- include/linux/poll.h | 2 ++ 3 files changed, 22 insertions(+), 17 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 3817149..728f56c 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -77,9 +77,6 @@ /* Maximum number of nesting allowed inside epoll sets */ #define EP_MAX_NESTS 4 -/* Maximum msec timeout value storeable in a long int */ -#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ) - #define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) #define EP_UNACTIVE_PTR ((void *) -1L) @@ -1116,18 +1113,22 @@ static int ep_send_events(struct eventpoll *ep, static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, int maxevents, long timeout) { - int res, eavail; + int res, eavail, timed_out = 0; unsigned long flags; - long jtimeout; + long slack; wait_queue_t wait; - - /* - * Calculate the timeout by checking for the "infinite" value (-1) - * and the overflow condition. The passed timeout is in milliseconds, - * that why (t * HZ) / 1000. - */ - jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ? - MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000; + struct timespec end_time; + ktime_t expires, *to = NULL; + + if (timeout > 0) { + ktime_get_ts(&end_time); + timespec_add_ns(&end_time, (u64)timeout * NSEC_PER_MSEC); + slack = estimate_accuracy(&end_time); + to = &expires; + *to = timespec_to_ktime(end_time); + } else if (timeout == 0) { + timed_out = 1; + } retry: spin_lock_irqsave(&ep->lock, flags); @@ -1149,7 +1150,7 @@ retry: * to TASK_INTERRUPTIBLE before doing the checks. */ set_current_state(TASK_INTERRUPTIBLE); - if (!list_empty(&ep->rdllist) || !jtimeout) + if (!list_empty(&ep->rdllist) || timed_out) break; if (signal_pending(current)) { res = -EINTR; @@ -1157,7 +1158,9 @@ retry: } spin_unlock_irqrestore(&ep->lock, flags); - jtimeout = schedule_timeout(jtimeout); + if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) + timed_out = 1; + spin_lock_irqsave(&ep->lock, flags); } __remove_wait_queue(&ep->wq, &wait); @@ -1175,7 +1178,7 @@ retry: * more luck. */ if (!res && eavail && - !(res = ep_send_events(ep, events, maxevents)) && jtimeout) + !(res = ep_send_events(ep, events, maxevents)) && !timed_out) goto retry; return res; diff --git a/fs/select.c b/fs/select.c index 500a669..003cb77 100644 --- a/fs/select.c +++ b/fs/select.c @@ -67,7 +67,7 @@ static long __estimate_accuracy(struct timespec *tv) return slack; } -static long estimate_accuracy(struct timespec *tv) +long estimate_accuracy(struct timespec *tv) { unsigned long ret; struct timespec now; diff --git a/include/linux/poll.h b/include/linux/poll.h index 600cc1f..52be81f 100644 --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -73,6 +73,8 @@ extern void poll_initwait(struct poll_wqueues *pwq); extern void poll_freewait(struct poll_wqueues *pwq); extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state, ktime_t *expires, unsigned long slack); +extern long estimate_accuracy(struct timespec *tv); + static inline int poll_schedule(struct poll_wqueues *pwq, int state) { -- 1.7.2.1 -- 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/