From: John Stultz <john.stultz@linaro.org>
To: lkml <linux-kernel@vger.kernel.org>
Cc: John Stultz <john.stultz@linaro.org>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Eric Dumazet <eric.dumazet@gmail.com>,
Richard Cochran <richardcochran@gmail.com>
Subject: [PATCH 6/9] time: Reduce timekeeper read lock hold time
Date: Thu, 1 Mar 2012 23:12:45 -0800 [thread overview]
Message-ID: <1330672368-32290-7-git-send-email-john.stultz@linaro.org> (raw)
In-Reply-To: <1330672368-32290-1-git-send-email-john.stultz@linaro.org>
Now that timekeeper updates are done with a shadow copy,
we can reduce the readlock hold time to only the update.
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
kernel/time/timekeeping.c | 5 ++---
1 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index ed8cb51..97982b1 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1071,7 +1071,6 @@ static void update_wall_time(void)
s64 remainder;
spin_lock_irqsave(&timekeeper_wlock, flags);
- write_seqcount_begin(&timekeeper_rlock);
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@@ -1155,13 +1154,13 @@ static void update_wall_time(void)
second_overflow();
}
-
+ write_seqcount_begin(&timekeeper_rlock);
timekeeper = shadow_tk;
timekeeper.clock->cycle_last = timekeeper.cycle_last;
timekeeping_update(&timekeeper, false);
+ write_seqcount_end(&timekeeper_rlock);
out:
- write_seqcount_end(&timekeeper_rlock);
spin_unlock_irqrestore(&timekeeper_wlock, flags);
}
--
1.7.3.2.146.gca209
next prev parent reply other threads:[~2012-03-02 7:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-02 7:12 [PATCH 0/9] Reduce timekeeping lock hold time v2 John Stultz
2012-03-02 7:12 ` [PATCH 1/9] time: Condense timekeeper.xtime into xtime_sec John Stultz
2012-03-02 21:13 ` Christoph Lameter
2012-03-03 5:54 ` Richard Cochran
2012-03-02 7:12 ` [PATCH 2/9] time: Rework timekeeping functions to take timekeeper ptr as argument John Stultz
2012-03-02 7:12 ` [PATCH 3/9] time: Split timekeeper lock into separate reader/writer locks John Stultz
2012-03-02 7:12 ` [PATCH 4/9] time: Update timekeeper structure using a local shadow John Stultz
2012-03-02 7:38 ` Ingo Molnar
2012-03-02 7:53 ` John Stultz
2012-03-02 8:07 ` Ingo Molnar
2012-03-02 7:12 ` [PATCH 5/9] time: Shadow cycle_last in timekeeper structure John Stultz
2012-03-02 7:12 ` John Stultz [this message]
2012-03-02 7:12 ` [PATCH 7/9] time: Convert the timekeeper's wlock to a raw_spin_lock John Stultz
2012-03-02 7:12 ` [PATCH 8/9] time: Whitespace cleanups per Ingo's requests John Stultz
2012-03-02 7:12 ` [PATCH 9/9] time: Explicitly use u32 instead of int for shift values John Stultz
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