>>>>> "Linus" == Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> writes: Linus> On Thu, Jul 3, 2014 at 11:22 AM, Linus Torvalds Linus> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: >> >> So the bugzilla entry worries me a bit - we definitely do not want to >> regress in case somebody really relied on timing - but without more >> specific information I still think the real bug is just in the >> man-page. Linus> Side note: the 2MB limit may be too small. 2M is peanuts on modern Linus> machines, even for fairly slow IO, and there are lots of files (like Linus> glibc etc) that people might want to read-ahead during boot. We Linus> already do bigger read-ahead if people just do "read()" system calls. Linus> So I could certainly imagine that we should increase it. Linus> I do *not* think we should bow down to insane man-pages that have Linus> always been wrong, though, and I don't think we should increase it to Linus> "let's just read-ahead a whole ISO image" kind of sizes.. This is one of those perenial questions of how to tune this. I agree we should increase the number, but shouldn't it be based on both the amount of memory in the machine, number of devices (or is it all just one big pool?) and the speed of the actual device doing readahead? Doesn't make sense to do 32mb of readahead on a USB 1.1 thumb drive or even a CDROM. But maybe it does for USB3 thumb drives? John -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>