From: John Stultz <john.stultz@linaro.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Eric Dumazet <eric.dumazet@gmail.com>,
Richard Cochran <richardcochran@gmail.com>
Subject: Re: [PATCH 15/16] time: Update tiemkeeper structure using a local shadow
Date: Thu, 17 Nov 2011 14:03:22 -0800 [thread overview]
Message-ID: <1321567402.25715.35.camel@work-vm> (raw)
In-Reply-To: <1321329846-14755-16-git-send-email-john.stultz@linaro.org>
On Mon, 2011-11-14 at 20:04 -0800, John Stultz wrote:
> Uses a local shadow structure to update the timekeeper. This
> reduces the timekeeper.lock hold time.
>
> WARNING: This introduces a race, but the window might be provably
> so small as to not be observable. This patch needs lots more math
> and comments to validate that assumption.
Bah. After thinking about it, this patch won't work, since it would
possibly lose updates via settimeofday(), etc.
So I'm coming around to Thomas' double lock reader-seq/writer-lock
method.
thanks
-john
next prev parent reply other threads:[~2011-11-17 22:05 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-15 4:03 [PATCH 00/16] Timekeeping cleanups and locking changes John Stultz
2011-11-15 4:03 ` [PATCH 01/16] time: Move total_sleep_time into the timekeeper structure John Stultz
2011-11-15 4:03 ` [PATCH 02/16] time: Move wall_to_monotonic " John Stultz
2011-11-15 4:03 ` [PATCH 03/16] time: Move xtime into timekeeeper structure John Stultz
2011-11-15 4:03 ` [PATCH 04/16] time: Move raw_time into timekeeper structure John Stultz
2011-11-15 4:03 ` [PATCH 05/16] time: Cleanup global variables and move them to the top John Stultz
2011-11-15 4:03 ` [PATCH 06/16] time: Add timekeeper lock John Stultz
2011-11-15 4:03 ` [PATCH 07/16] ntp: Cleanup timex.h John Stultz
2011-11-15 4:03 ` [PATCH 08/16] ntp: Access tick_length variable via ntp_tick_length() John Stultz
2011-11-15 4:03 ` [PATCH 09/16] ntp: Add ntp_lock to replace xtime_locking John Stultz
2011-11-15 4:04 ` [PATCH 10/16] time: Remove most of xtime_lock usage in timekeeping.c John Stultz
2011-11-15 4:04 ` [PATCH 11/16] time: Reorder so the hot data is together John Stultz
2011-11-15 4:04 ` [PATCH 12/16] time: Move common updates to a function John Stultz
2011-11-15 4:04 ` [PATCH 13/16] time: Condense timekeeper.xtime into xtime_sec John Stultz
2011-11-15 4:04 ` [PATCH 14/16] time: Rework timekeeping functions to take timekeeper ptr as argument John Stultz
2011-11-15 4:04 ` [PATCH 15/16] time: Update tiemkeeper structure using a local shadow John Stultz
2011-11-17 22:03 ` John Stultz [this message]
2011-11-15 4:04 ` [PATCH 16/16] time: Rework update_vsyscall to pass timekeeper John Stultz
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