[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20080726154029.GA15945@elte.hu>
Date: Sat, 26 Jul 2008 17:40:29 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Martin Wilck <martin.wilck@...itsu-siemens.com>
Cc: Cyrill Gorcunov <gorcunov@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"H. Peter Anvin" <hpa@...or.com>,
"Wichert, Gerhard" <Gerhard.Wichert@...itsu-siemens.com>,
"Maciej W. Rozycki" <macro@...ux-mips.org>
Subject: Re: [PATCH] x86 (64): make calibrate_APIC_clock() SMI-safe (take 3)
* Martin Wilck <martin.wilck@...itsu-siemens.com> wrote:
> [PATCH] x86 (64): make calibrate_APIC_clock() SMI-safe (take 3)
>
> Non-maskable asynchronous events (e.g. SMIs) which occur during the
> APIC timer calibration can cause timer miscalibrations, sometimes by
> large amounts. This patch fixes this by making sure that no
> significant interruption occurs between APIC and TSC reads. SMIs may
> still occur at some stage in the calibration loop, causing the loop to
> last longer than intended. This doesn't matter though, as long as the
> start and end values are both taken simultaneously.
>
> Changed wrt take 2: Use max. possible start value for the APIC timer
> to avoid underflow.
>
> Signed-off-by: Martin Wilck <martin.wilck@...itsu-siemens.com>
> Signed-off-by: Gerhard Wichert <gerhard.wichert@...itsu-siemens.com>
>
> --- arch/x86/kernel/apic_64.c 2008-07-25 15:39:51.000000000 +0200
> +++ arch/x86/kernel/apic_64.c.new 2008-07-25 15:55:08.000000000 +0200
nice - could you please implement it symmetrically on 32-bit APIC
calibration as well?
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists