Messages in this thread | | | Date | Fri, 3 Apr 2009 02:09:01 +0100 | From | Matthew Garrett <> | Subject | Re: Ext4 and the "30 second window of death" |
| |
On Thu, Apr 02, 2009 at 05:59:53PM -0700, david@lang.hm wrote:
> is laptop mode > > A. "write everything now, don't delay writes" in the hope that the drive > will be idle enough later to spin down
laptop-mode doesn't delay writes. Ever.
> or > > B. "delay all writes until later, then when the drive wakes up do all > pending writes at that time" so that the drive can go to sleep in the > meantime?
Yes.
> I've heard things in these threads that would indicate both behaviors.
The code's pretty trivial. The only real functional differences laptop-mode brings are to write out all dirty pages (rather than just writing down to the watermark) and to call sys_sync() a few seconds after the last thing that hit disk rather than being satisfied from cache. It's entirely a mechanism to opportunistically take advantage of the disk being spun up.
-- Matthew Garrett | mjg59@srcf.ucam.org
| |