Messages in this thread | | | Subject | Re: [PATCH 4/4] FUSE: implement direct mmap | From | Miklos Szeredi <> | Date | Thu, 09 Jul 2009 12:35:26 +0200 |
| |
On Thu, 09 Jul 2009, Tejun Heo wrote: > >> Using non-swappable memory would be fine for most device emulations > >> but mapping large amount of pages would be problematic. Hmmm... this > >> is difficult. It's a compromise among flexibility, scalability and > >> code complexity. > > > > What's the difficulty? > > The desire to avoid pinning all the mapped pages. :-) > > > Allocating pages, giving them an ID and mapping them into various page > > tables seems simple in contrast to trying to make a tmpfs file be a > > fuse file at the same time, which the VM is really not prepared for. > > If pinning all the pages are okay, the above should work fine.
If the page allocation is privileged then I think it's okay.
I have only vague ideas how this "direct mmap" could be used for other things than sound drivers. For example there's a significant push towards making network filesystems coherent. This is currently not well supported by fuse and adding coherency guarantees to mmap is especially tricky. But I'm not sure it really needs a special mmap interface, that's just one of the options.
Thoughts?
Thanks, Miklos
| |