Date: Sun, 26 Jan 2014 22:08:50 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Len Brown <lenb@kernel.org>
Cc: rjw@sisk.pl, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Len Brown <len.brown@intel.com>
Subject: Re: [PATCH 1/1] suspend: make sync() on suspend-to-RAM optional
Message-ID: <20140126210850.GA7246@Nokia-N900>
References: <ce1b9fc9cdcfd1fe8f9f3b8570421271dc15ae75.1390460951.git.len.brown@intel.com>
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Hi!

> From: Len Brown <len.brown@intel.com>
> 
> Linux suspend-to-RAM was unreliable when first developed,
> and so sys_sync() was invoked inside the kernel at the
> start of every suspend flow.
> 
> Today, many devices are invoking suspend with
> high reliability and high frequency, and they don't
> want to be forced to pay for sync on every suspend.
> 
> So here we make it optional.
> De-select CONFIG_PM_SLEEP_SYNC to delete the call entirely.
> or keep CONFIG_PM_SLEEP and you can now clear the
> sys/power/sleep_sync attribte to disable the sync
> from user-space.

Dunno. Config option plus sysfs attribute is overdoing it a bit.
Maybe we could do

echo memfast > state

to enter suspend without sync? Patch should be simpler that way,
and we won't have to keep the state...

						Pavel
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