On 05/08/2015 09:14 PM, Linus Torvalds wrote: > On Fri, May 8, 2015 at 9:59 AM, Rik van Riel <riel@xxxxxxxxxx> wrote: >> >> However, for persistent memory, all of the files will be "in memory". > > Yes. However, I doubt you will find a very sane rw filesystem that > then also makes them contiguous and aligns them at 2MB boundaries. > > Anything is possible, I guess, but things like that are *hard*. The > fragmentation issues etc cause it to a really challenging thing. The TLB performance bonus of accessing the large files with large pages may make it worthwhile to solve that hard problem. > And if they aren't aligned big contiguous allocations, then they > aren't relevant from any largepage cases. You'll still have to map > them 4k at a time etc. Absolutely, but we only need the 4k struct pages when the files are mapped. I suspect a lot of the files will just sit around idle, without being used. I am not convinced that the idea I wrote down earlier in this thread is worthwhile now, but it may turn out to be at some point in the future. It all depends on how much data people store on DAX filesystems, and how many files they have open at once. -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
