On Mon, 5 Nov 2012 14:46:57 -0800 Michel Lespinasse <walken@xxxxxxxxxx> wrote: > Earlier this year, Rik proposed using augmented rbtrees to optimize > our search for a suitable unmapped area during mmap(). This prompted > my work on improving the augmented rbtree code. Rik doesn't seem to > have time to follow up on his idea at this time, so I'm sending this > series to revive the idea. Well, the key word here is "optimize". Some quantitative testing results would be nice, please! People do occasionally see nasty meltdowns in the get_unmapped_area() vicinity. There was one case 2-3 years ago which was just ghastly, but I can't find the email (it's on linux-mm somewhere). This one might be another case: http://lkml.indiana.edu/hypermail/linux/kernel/1101.1/00896.html If you can demonstrate that this patchset fixes some of all of the bad search complexity scenarios then that's quite a win? > These changes are against v3.7-rc4. I have not converted all applicable > architectuers yet, but we don't necessarily need to get them all onboard > at once - the series is fully bisectable and additional architectures > can be added later on. I am confident enough in my tests for patches 1-8; > however the second half of the series basically didn't get tested as > I don't have access to all the relevant architectures. Yes, I'll try to get these into -next so that the thousand monkeys at least give us some compilation coverage testing. Hopefully the relevant arch maintainers will find time to perform a runtime test. > Patch 1 is the validate_mm() fix from Bob Liu (+ fixed-the-fix from me :) I grabbed this one separately, as a post-3.6 fix. -- 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>