On Sun, May 10, 2015 at 9:44 PM, Dave Chinner [off-list ref] wrote:

...Please explain what your use case is that makes this
so prohibitively expensive it needs to be removed.

wake on packet, process packet without turning on the display,
immediately suspend.  Do this potentially several times per second.

quoted

The user-space utilities s2ram and s2disk choose to invoke sync() today.
A user can invoke suspend directly via /sys/power/state to skip that cost.

So, you want to have s2disk write all the dirty pages in memory to
the suspend image, rather than to the filesystem?

The s2disk utility is unchanged by this proposal, it already includes a sync().

cheers,
Len Brown, Intel Open Source Technology Center