|From:||Andrea Arcangeli <email@example.com>|
|To:||Peter Zijlstra <firstname.lastname@example.org>|
|Subject:||[RFC] AutoNUMA alpha6|
|Date:||Fri, 16 Mar 2012 19:25:11 +0100|
|Cc:||Linus Torvalds <email@example.com>, Andrew Morton <firstname.lastname@example.org>, Thomas Gleixner <email@example.com>, Ingo Molnar <firstname.lastname@example.org>, Paul Turner <email@example.com>, Suresh Siddha <firstname.lastname@example.org>, Mike Galbraith <email@example.com>, "Paul E. McKenney" <firstname.lastname@example.org>, Lai Jiangshan <email@example.com>, Dan Smith <firstname.lastname@example.org>, Bharata B Rao <email@example.com>, Lee Schermerhorn <Lee.Schermerhorn@hp.com>, Rik van Riel <firstname.lastname@example.org>, Johannes Weiner <email@example.com>, firstname.lastname@example.org, email@example.com|
On Fri, Mar 16, 2012 at 03:40:28PM +0100, Peter Zijlstra wrote: > And a few numbers... Could you try my two trivial benchmarks I sent on lkml too? That should take less time than the effort you did to add those performance numbers to perf. I use those benchmarks as a regression test for my code. They exercise a more complex scenario than "sleep 2" so supposedly the results will be more interesting. You find both programs in this link: http://lists.openwall.net/linux-kernel/2012/01/27/9 These are my results. http://www.kernel.org/pub/linux/kernel/people/andrea/auto... I happened to have released the autonuma source yesterday on my git tree: http://git.kernel.org/?p=linux/kernel/git/andrea/aa.git;a... git clone --reference linux -b autonuma git://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git http://git.kernel.org/?p=linux/kernel/git/andrea/aa.git;a... It's a big monlithic patch, but I'll split it. THP native migration isn't complete yet so it degrades more than it should when comparing THP autonuma vs hard bind THP. But that can be done later and it'll benefit move_pages or any other userland hard binding too, not just the autonuma kernel side. I guess you need this feature too. The scanning rate must be tuned, it's possibly too fast as default because all my benchmarks tends to be short lived. There's already lots of tuning available in /sys/kernel/mm/autonuma . There's lots of other tuning to facilitate testing the different algorithms. By default the numa balancing decisions will keep the process stuck in its own node, unless there's an idle cpu, but there's a model to let it escape the node for load balancing/fairness reasons (to be closer to the stock scheduler) by setting load_balance_strict to zero (default is 1). There's also a knuma_scand/working_set tweak to scan the working set and not all memory (so only care about what's hot, if the app has a ton of memory that isn't using in some node, that won't be accounted anymore in the memory migration and CPU migration decisions). There's no syscall or hint userland can give. The migration doesn't happen during page fault. There's proper knuma_migrated daemon per node. The daemon has per-node array of page-lists. Then knuma_migrated0 is waken with some hysteresis, and will pick pages that wants to go from node1 to node0, from node 2 to node0 etc.. and it'll pick them in round robin fascion across all nodes. That stops when the node0 is out of memory and the cache would be shrunk or in most cases when there aren't more pages to migrate. One of the missing features is to start balancing cache around but I'll add that later and I've already reserved one slot in the pgdat for that. All other numa_migratedN also runs, so we're guaranteed to make progress when process A going from node0 to node1, and process B going from node1 to node0. All memory that isn't shared is migrated, that includes mapped pagecache. The basic logic is scheduler following the memory and memory following CPU, until things converge. I'm skeptical in general that any NUMA hinting syscall will be used by anything except qemu and that's what motivated my design. Hopefully in the future CPU vendors will provide us a better way to track memory locality than what I'm doing right now in software. The cost is almost unmeasurable (even if you disable the pmd mode). I'm afraid with virt the cost could be higher because of the vmexists but virt is long lived and a slower scanning rate for the memory layout info should be ok. Here also huge amount of improvements are possible. Hopefully it's not too intrusive either. I also wrote a threaded userland tool that can render visually at >20frames per sec the status of the memory and shows the memory migration (the ones I found were on python and with >8G of ram they just can't deliver). I was going to try to make it per-process instead of global before releasing it, that may give another speedup (or slowdown I don't know for sure). It'll help explain what the code does and see it in action. But for us echo 1 >/sys/kernel/mm/autonuma/debug may be enough. Still the visual thing is cool and if done generically it would be interesting. Ideally once it goes per process it should show which CPU the process is running on too, not just where the process memory is. arch/x86/include/asm/paravirt.h | 2 - arch/x86/include/asm/pgtable.h | 51 ++- arch/x86/include/asm/pgtable_types.h | 22 +- arch/x86/kernel/cpu/amd.c | 4 +- arch/x86/kernel/cpu/common.c | 4 +- arch/x86/kernel/setup_percpu.c | 1 + arch/x86/mm/gup.c | 2 +- arch/x86/mm/numa.c | 9 +- fs/exec.c | 3 + include/asm-generic/pgtable.h | 13 + include/linux/autonuma.h | 41 + include/linux/autonuma_flags.h | 62 ++ include/linux/autonuma_sched.h | 61 ++ include/linux/autonuma_types.h | 54 ++ include/linux/huge_mm.h | 7 +- include/linux/kthread.h | 1 + include/linux/mm_types.h | 29 + include/linux/mmzone.h | 6 + include/linux/sched.h | 4 + kernel/exit.c | 1 + kernel/fork.c | 36 +- kernel/kthread.c | 23 + kernel/sched/Makefile | 3 +- kernel/sched/core.c | 13 +- kernel/sched/fair.c | 55 ++- kernel/sched/numa.c | 322 ++++++++ kernel/sched/sched.h | 12 + mm/Kconfig | 13 + mm/Makefile | 1 + mm/autonuma.c | 1465 ++++++++++++++++++++++++++++++++++ mm/huge_memory.c | 32 +- mm/memcontrol.c | 2 +- mm/memory.c | 36 +- mm/mempolicy.c | 15 +- mm/mmu_context.c | 2 + mm/page_alloc.c | 19 + 36 files changed, 2376 insertions(+), 50 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to firstname.lastname@example.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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