Messages in this thread | | | Date | Thu, 26 Mar 2009 20:02:58 +0000 | From | Matthew Garrett <> | Subject | Re: ext3 IO latency measurements (was: Linux 2.6.29) |
| |
On Thu, Mar 26, 2009 at 06:59:00PM +0000, Alan Cox wrote: > > And what's the argument for not doing it in the kernel? > > > > The fact is, "atime" by default is just wrong. > > It probably was a wrong default - twenty years ago. Actually it may well > have been a wrong default in Unix v6 8) > > However > - atime behaviour is SuS required
SuS says "An implementation may update fields that are marked for update immediately, or it may update such fields periodically. At an update point in time, any marked fields shall be set to the current time and the update marks shall be cleared" but doesn't appear to specify any kind of time limit. A conforming implementation could wait a century before performing the update. So while relatime doesn't conform, the practical difference is meaningless. You can't depend on atime being updated in a timely manner.
-- Matthew Garrett | mjg59@srcf.ucam.org
| |