linux-kernel - Re: [RFC][PATCH -mm] PM: Do not sync from within the freezer during suspend to RAM

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Message-Id: <200707050848.16163.nigel@nigel.suspend2.net>
Date:	Thu, 5 Jul 2007 08:48:15 +1000
From:	Nigel Cunningham <nigel@...el.suspend2.net>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Oliver Neukum <oliver@...kum.org>, Pavel Machek <pavel@....cz>,
	Paul Mackerras <paulus@...ba.org>,
	Miklos Szeredi <miklos@...redi.hu>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC][PATCH -mm] PM: Do not sync from within the freezer during suspend to RAM

Hi.

On Thursday 05 July 2007 00:58:58 Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> The syncing of filesystems from within the freezer in not needed for suspend 
to
> RAM.  Change freeze_processes() so that it doesn't execute sys_sync() and
> introduce the "syncing" version of it to be called from the hibernation code
> paths.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  include/linux/freezer.h |   14 ++++++++++++--
>  kernel/power/disk.c     |    2 +-
>  kernel/power/main.c     |    6 ++++++
>  kernel/power/process.c  |    8 +++++---
>  kernel/power/user.c     |    2 +-
>  5 files changed, 25 insertions(+), 7 deletions(-)

Looks ok, except that I wonder if you want the following fragment. It looks to 
me (looking at rc6) like with this code, you'll currently call sys_sync twice 
when suspending to ram. Maybe I'm misreading it. Also, shouldn't it be done 
after taking the mutex?

Regards,

Nigel

> @@ -231,6 +232,11 @@ static int enter_state(suspend_state_t s
>  
>  	if (!valid_state(state))
>  		return -ENODEV;
> +
> +	printk("Syncing filesystems ... ");
> +	sys_sync();
> +	printk("done.\n");
> +
>  	if (!mutex_trylock(&pm_mutex))
>  		return -EBUSY;
>  


-- 
Nigel, Michelle and Alisdair Cunningham
5 Mitchell Street
Cobden 3266
Victoria, Australia

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