From a0715cc22601e8830ace98366c0c2bd8da52af52 Mon Sep 17 00:00:00 2001 From: Alex Thorlton Date: Mon, 7 Apr 2014 15:37:10 -0700 Subject: mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE Add VM_INIT_DEF_MASK, to allow us to set the default flags for VMs. It also adds a prctl control which allows us to set the THP disable bit in mm->def_flags so that VMs will pick up the setting as they are created. Signed-off-by: Alex Thorlton Suggested-by: Oleg Nesterov Cc: Gerald Schaefer Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Christian Borntraeger Cc: Paolo Bonzini Cc: "Kirill A. Shutemov" Cc: Mel Gorman Acked-by: Rik van Riel Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Andrea Arcangeli Cc: Oleg Nesterov Cc: "Eric W. Biederman" Cc: Alexander Viro Cc: Johannes Weiner Cc: David Rientjes Cc: Paolo Bonzini Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index abc45890f0a5..e40c0a01d5a6 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -530,8 +530,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) atomic_set(&mm->mm_count, 1); init_rwsem(&mm->mmap_sem); INIT_LIST_HEAD(&mm->mmlist); - mm->flags = (current->mm) ? - (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; mm->core_state = NULL; atomic_long_set(&mm->nr_ptes, 0); memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); @@ -540,8 +538,15 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) mm_init_owner(mm, p); clear_tlb_flush_pending(mm); - if (likely(!mm_alloc_pgd(mm))) { + if (current->mm) { + mm->flags = current->mm->flags & MMF_INIT_MASK; + mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; + } else { + mm->flags = default_dump_filter; mm->def_flags = 0; + } + + if (likely(!mm_alloc_pgd(mm))) { mmu_notifier_mm_init(mm); return mm; } -- cgit v1.2.3 From 615d6e8756c87149f2d4c1b93d471bca002bd849 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Mon, 7 Apr 2014 15:37:25 -0700 Subject: mm: per-thread vma caching This patch is a continuation of efforts trying to optimize find_vma(), avoiding potentially expensive rbtree walks to locate a vma upon faults. The original approach (https://lkml.org/lkml/2013/11/1/410), where the largest vma was also cached, ended up being too specific and random, thus further comparison with other approaches were needed. There are two things to consider when dealing with this, the cache hit rate and the latency of find_vma(). Improving the hit-rate does not necessarily translate in finding the vma any faster, as the overhead of any fancy caching schemes can be too high to consider. We currently cache the last used vma for the whole address space, which provides a nice optimization, reducing the total cycles in find_vma() by up to 250%, for workloads with good locality. On the other hand, this simple scheme is pretty much useless for workloads with poor locality. Analyzing ebizzy runs shows that, no matter how many threads are running, the mmap_cache hit rate is less than 2%, and in many situations below 1%. The proposed approach is to replace this scheme with a small per-thread cache, maximizing hit rates at a very low maintenance cost. Invalidations are performed by simply bumping up a 32-bit sequence number. The only expensive operation is in the rare case of a seq number overflow, where all caches that share the same address space are flushed. Upon a miss, the proposed replacement policy is based on the page number that contains the virtual address in question. Concretely, the following results are seen on an 80 core, 8 socket x86-64 box: 1) System bootup: Most programs are single threaded, so the per-thread scheme does improve ~50% hit rate by just adding a few more slots to the cache. +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 50.61% | 19.90 | | patched | 73.45% | 13.58 | +----------------+----------+------------------+ 2) Kernel build: This one is already pretty good with the current approach as we're dealing with good locality. +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 75.28% | 11.03 | | patched | 88.09% | 9.31 | +----------------+----------+------------------+ 3) Oracle 11g Data Mining (4k pages): Similar to the kernel build workload. +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 70.66% | 17.14 | | patched | 91.15% | 12.57 | +----------------+----------+------------------+ 4) Ebizzy: There's a fair amount of variation from run to run, but this approach always shows nearly perfect hit rates, while baseline is just about non-existent. The amounts of cycles can fluctuate between anywhere from ~60 to ~116 for the baseline scheme, but this approach reduces it considerably. For instance, with 80 threads: +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 1.06% | 91.54 | | patched | 99.97% | 14.18 | +----------------+----------+------------------+ [akpm@linux-foundation.org: fix nommu build, per Davidlohr] [akpm@linux-foundation.org: document vmacache_valid() logic] [akpm@linux-foundation.org: attempt to untangle header files] [akpm@linux-foundation.org: add vmacache_find() BUG_ON] [hughd@google.com: add vmacache_valid_mm() (from Oleg)] [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: adjust and enhance comments] Signed-off-by: Davidlohr Bueso Reviewed-by: Rik van Riel Acked-by: Linus Torvalds Reviewed-by: Michel Lespinasse Cc: Oleg Nesterov Tested-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index e40c0a01d5a6..bc0e96b78dfd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -28,6 +28,8 @@ #include #include #include +#include +#include #include #include #include @@ -364,7 +366,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) mm->locked_vm = 0; mm->mmap = NULL; - mm->mmap_cache = NULL; + mm->vmacache_seqnum = 0; mm->map_count = 0; cpumask_clear(mm_cpumask(mm)); mm->mm_rb = RB_ROOT; @@ -882,6 +884,9 @@ static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) if (!oldmm) return 0; + /* initialize the new vmacache entries */ + vmacache_flush(tsk); + if (clone_flags & CLONE_VM) { atomic_inc(&oldmm->mm_users); mm = oldmm; -- cgit v1.2.3 From 514ddb446c5c5a238eca32b7052b7a8accae4e93 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 7 Apr 2014 15:37:27 -0700 Subject: fork: collapse copy_flags into copy_process copy_flags() does not use the clone_flags formal and can be collapsed into copy_process() for cleaner code. Signed-off-by: David Rientjes Cc: Johannes Weiner Cc: Michal Hocko Cc: KAMEZAWA Hiroyuki Cc: Christoph Lameter Cc: Pekka Enberg Cc: Tejun Heo Cc: Mel Gorman Cc: Oleg Nesterov Cc: Rik van Riel Cc: Jianguo Wu Cc: Tim Hockin Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index bc0e96b78dfd..c777964c0662 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1080,15 +1080,6 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) return 0; } -static void copy_flags(unsigned long clone_flags, struct task_struct *p) -{ - unsigned long new_flags = p->flags; - - new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); - new_flags |= PF_FORKNOEXEC; - p->flags = new_flags; -} - SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) { current->clear_child_tid = tidptr; @@ -1238,7 +1229,8 @@ static struct task_struct *copy_process(unsigned long clone_flags, goto bad_fork_cleanup_count; delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ - copy_flags(clone_flags, p); + p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); + p->flags |= PF_FORKNOEXEC; INIT_LIST_HEAD(&p->children); INIT_LIST_HEAD(&p->sibling); rcu_copy_process(p); -- cgit v1.2.3 From f0432d159601f96839f514f286eaa5b75c4112dc Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 7 Apr 2014 15:37:30 -0700 Subject: mm, mempolicy: remove per-process flag PF_MEMPOLICY is an unnecessary optimization for CONFIG_SLAB users. There's no significant performance degradation to checking current->mempolicy rather than current->flags & PF_MEMPOLICY in the allocation path, especially since this is considered unlikely(). Running TCP_RR with netperf-2.4.5 through localhost on 16 cpu machine with 64GB of memory and without a mempolicy: threads before after 16 1249409 1244487 32 1281786 1246783 48 1239175 1239138 64 1244642 1241841 80 1244346 1248918 96 1266436 1254316 112 1307398 1312135 128 1327607 1326502 Per-process flags are a scarce resource so we should free them up whenever possible and make them available. We'll be using it shortly for memcg oom reserves. Signed-off-by: David Rientjes Cc: Johannes Weiner Cc: Michal Hocko Cc: KAMEZAWA Hiroyuki Cc: Christoph Lameter Cc: Pekka Enberg Cc: Tejun Heo Cc: Mel Gorman Cc: Oleg Nesterov Cc: Rik van Riel Cc: Jianguo Wu Cc: Tim Hockin Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index c777964c0662..e905e9c6b224 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1276,7 +1276,6 @@ static struct task_struct *copy_process(unsigned long clone_flags, p->mempolicy = NULL; goto bad_fork_cleanup_threadgroup_lock; } - mpol_fix_fork_child_flag(p); #endif #ifdef CONFIG_CPUSETS p->cpuset_mem_spread_rotor = NUMA_NO_NODE; -- cgit v1.2.3 From 52f5684c8e1ec7463192aba8e2916df49807511a Mon Sep 17 00:00:00 2001 From: Gideon Israel Dsouza Date: Mon, 7 Apr 2014 15:39:20 -0700 Subject: kernel: use macros from compiler.h instead of __attribute__((...)) To increase compiler portability there is which provides convenience macros for various gcc constructs. Eg: __weak for __attribute__((weak)). I've replaced all instances of gcc attributes with the right macro in the kernel subsystem. Signed-off-by: Gideon Israel Dsouza Cc: "Rafael J. Wysocki" Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index e905e9c6b224..54a8d26f612f 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -73,6 +73,7 @@ #include #include #include +#include #include #include @@ -286,7 +287,7 @@ void __init fork_init(unsigned long mempages) init_task.signal->rlim[RLIMIT_NPROC]; } -int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, +int __weak arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { *dst = *src; -- cgit v1.2.3