Hi! > > > Yep, I call that suspend-to-both. It is planned, but not really > > > trivial, and I'm a little busy. If someone wants to help.... > > > > I was thinking a few days ago. With your move of all this stuff to > > userspace, if it was done in multiple stages, we could implement > > a form of checkpointing this way. > > > > So instead of doing the 'suspend to disk/ram' after 'write out all pages', > > we just continue. > > > > Why is this useful ? We've seen bugs reported that only ever bite > > customers after they've run their workload for a month. Now, if they had a > > means of checkpointing, then when it crashes, they could capture the last > > image that landed somewhere, and set that up for more tests/monitoring with > > kprobes etc and reproduce those hard-to-reproduce bugs a lot faster. > > I've been asked about this from time to time too. Apart from the issues Pavel > has already mentioned, the big problem in my mind was figuring out what to do > about disk storage. As the algorithm stands at the moment, the image includes > information about the state of mounted filesystems. We'd need to somehow get > rid of or be able to ignore that. Any suggestions? Well, copying all the filesystems would work, as would having no filesystems at all :-) [ramdisk case]. And perhaps practical equivalent of "copy all filesystems" can be done with device mapper. [Of course, you'd have to copy all the filesystems back before doing resume]. Pavel -- 116:
