On Mon, 2010-10-18 at 20:19 +0200, Ingo Molnar wrote: > I think it would be fair to argue that #2 is the thing that should be fixed first > and foremost - before touching any data structure details. > > Because if you fix #2 then all the other items will become no-op to 99.9% of the > people who are affected by this bug today. Where I stand at the end of the day: Executive summary for the TLDNR crowd: Before upcoming patch series IMA wasted 4,720k of memory on my test box when not configured to do anything. After patches IMA wastes 120k when not configured to do anything. ------------------------ I'm considering a system with 5000 inodes in core and 1500 inodes which IMA thinks should be measured (if it's on). (which just so happens to be close to the system I've been testing on shortly after reboot) I'm going to consider 6 cases of memory usage and will post the patches shortly after this mail. My cases are going to be: Linus - IMA Enabled Linus - IMA Disabled Allocate iint only when needed - IMA Enabled Allocate iint only when needed - IMA Disabled Allocate iint + RBTREE - IMA Enabled allocate iint + RBTREE - IMA Disabled In each case I consider 'disabled' to be 'compiled in but you didn't tell it to do anything.' So for Linus: sizeof(iint) = 312 sizeof(radix) = 632 sizeof(inode delta) = 0 (how much I grew struct inode) Given my scenario of a stock F14ish machine where 5000 inodes in core and 1500 are IMA relevant when enabled we end up with: Linus - Enabled Linus - Disabled ------------------ ---------------- iint_cache = 1,560k iint_cache = 1,560k radix = 3,160k radix = 3,160k inode d = 0 inode d = 0 total = 4,720k total = 4,720k For Allocate iint only when needed: sizeof(iint) = 288 sizeof(radix) = 632 sizeof(inode delta) = 24 (24 bytes from iint move to struct inode) Allocate iint - Enabled Alloce iint - Disabled ----------------------- ---------------------- iint_cache = 342k iint_cache = 0 radix = 948k radix = 0 inode d = 120k inode d = 120k total = 1,410k total = 120k For allocate iint only when needed and use rbtrees: sizeof(iint) = 320 sizeof(radix) = 632 (but irrelevant) sizeof(inode delta) = 24 Allocate + RBTREE - Enabled Allocate iint + RBTREE - Disabled --------------------------- --------------------------------- iint_cache = 480k iint_cache = 0 radix = 0 radix = 0 inode d = 120k inode d = 120k total = 600k total = 120k Seems like about the best we can do. This patch series attempts to addresses all 3 of the problems I believe we identified (we still serialize IMA relevant inodes but not the majority of them and none when IMA is not enabled) IMA will continue to waste 24 bytes per inode in core even when it isn't doing anything useful just by compiling it in. Future work to use a freezer could get rid of this if the complexity is worth the tradeoff. But I don't think it's worth it tonight. -Eric _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
