>>>>> "Linus" == Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes: Linus> On Fri, May 8, 2015 at 7:40 AM, John Stoffel <john@xxxxxxxxxxx> wrote: >> >> Now go and look at your /home or /data/ or /work areas, where the >> endusers are actually keeping their day to day work. Photos, mp3, >> design files, source code, object code littered around, etc. Linus> However, the big files in that list are almost immaterial from a Linus> caching standpoint. Linus> Caching source code is a big deal - just try not doing it and Linus> you'll figure it out. And the kernel C source files used to Linus> have a median size around 4k. Caching any files is a big deal, and if I'm doing batch edits of large jpegs, won't they get cached as well? Linus> The big files in your home directory? Let me make an educated Linus> guess. Very few to *none* of them are actually in your page Linus> cache right now. And you'd never even care if they ever made Linus> it into your page cache *at*all*. Much less whether you could Linus> ever cache them using large pages using some very fancy cache. Hmm... probably not honestly, since I'm not a home and not using the system actively right now. But I can see situations where being able to mix different page sizes efficiently might be a good thing. Linus> There are big files that care about caches, but they tend to be Linus> binaries, and for other reasons (things like randomization) you Linus> would never want to use largepages for those anyway. Or large design files, like my users at $WORK use, which can be 4Gb in size for a large design, which is ASIC chip layout work. So I'm a little bit in the minority there. And yes I do have other users will millions of itty bitty files as well. Linus> So from a page cache standpoint, I think the 4kB size still Linus> matters. A *lot*. largepages are a complete red herring, and Linus> will continue to be so pretty much forever (anonymous Linus> largepages perhaps less so). I think in the future, being able to efficiently mix page sizes will become useful, if only to lower the memory overhead of keeping track of large numbers of pages. John -- 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
