| Message ID | 20240722123320.2382992-1-hezhongkun.hzk@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/numa_balancing: Fix the memory thrashing problem in the single-threaded process | expand |
Zhongkun He <hezhongkun.hzk@bytedance.com> writes: > I found a problem in my test machine that the memory of a process is > repeatedly migrated between two nodes and does not stop. > > 1.Test step and the machines. > ------------ > VM machine: 4 numa nodes and 10GB per node. > > stress --vm 1 --vm-bytes 12g --vm-keep > > The info of numa stat: > while :;do cat memory.numa_stat | grep -w anon;sleep 5;done > anon N0=98304 N1=0 N2=10250747904 N3=2634334208 > anon N0=98304 N1=0 N2=10250747904 N3=2634334208 > anon N0=98304 N1=0 N2=9937256448 N3=2947825664 > anon N0=98304 N1=0 N2=8863514624 N3=4021567488 > anon N0=98304 N1=0 N2=7789772800 N3=5095309312 > anon N0=98304 N1=0 N2=6716030976 N3=6169051136 > anon N0=98304 N1=0 N2=5642289152 N3=7242792960 > anon N0=98304 N1=0 N2=5105442816 N3=7779639296 > anon N0=98304 N1=0 N2=5105442816 N3=7779639296 > anon N0=98304 N1=0 N2=4837007360 N3=8048074752 > anon N0=98304 N1=0 N2=3763265536 N3=9121816576 > anon N0=98304 N1=0 N2=2689523712 N3=10195558400 > anon N0=98304 N1=0 N2=2515148800 N3=10369933312 > anon N0=98304 N1=0 N2=2515148800 N3=10369933312 > anon N0=98304 N1=0 N2=2515148800 N3=10369933312 > anon N0=98304 N1=0 N2=3320455168 N3=9564626944 > anon N0=98304 N1=0 N2=4394196992 N3=8490885120 > anon N0=98304 N1=0 N2=5105442816 N3=7779639296 > anon N0=98304 N1=0 N2=6174195712 N3=6710886400 > anon N0=98304 N1=0 N2=7247937536 N3=5637144576 > anon N0=98304 N1=0 N2=8321679360 N3=4563402752 > anon N0=98304 N1=0 N2=9395421184 N3=3489660928 > anon N0=98304 N1=0 N2=10247872512 N3=2637209600 > anon N0=98304 N1=0 N2=10247872512 N3=2637209600 > > 2. Root cause: > Since commit 3e32158767b0 ("mm/mprotect.c: don't touch single threaded > PTEs which are on the right node")the PTE of local pages will not be > changed in change_pte_range() for single-threaded process, so no > page_faults information will be generated in do_numa_page(). If a > single-threaded process has memory on another node, it will > unconditionally migrate all of it's local memory to that node, > even if the remote node has only one page. > > So, let's fix it. The memory of single-threaded process should follow > the cpu, not the numa faults info in order to avoid memory thrashing. Show the test results (numa stats) of the fixed kernel? > Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com> > --- > kernel/sched/fair.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 24dda708b699..d7cbbda568fb 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -2898,6 +2898,12 @@ static void task_numa_placement(struct task_struct *p) > numa_group_count_active_nodes(ng); > spin_unlock_irq(group_lock); > max_nid = preferred_group_nid(p, max_nid); > + } else if (atomic_read(&p->mm->mm_users) == 1) { > + /* > + * The memory of a single-threaded process should > + * follow the CPU in order to avoid memory thrashing. > + */ > + max_nid = numa_node_id(); > } > > if (max_faults) { The change looks reasonable for me, Thanks! Acked-by: "Huang, Ying" <ying.huang@intel.com> -- Best Regards, Huang, Ying
On Tue, Jul 23, 2024 at 11:39 AM Huang, Ying <ying.huang@intel.com> wrote: > > Zhongkun He <hezhongkun.hzk@bytedance.com> writes: > > > I found a problem in my test machine that the memory of a process is > > repeatedly migrated between two nodes and does not stop. > > > > 1.Test step and the machines. > > ------------ > > VM machine: 4 numa nodes and 10GB per node. > > > > stress --vm 1 --vm-bytes 12g --vm-keep > > > > The info of numa stat: > > while :;do cat memory.numa_stat | grep -w anon;sleep 5;done > > anon N0=98304 N1=0 N2=10250747904 N3=2634334208 > > anon N0=98304 N1=0 N2=10250747904 N3=2634334208 > > anon N0=98304 N1=0 N2=9937256448 N3=2947825664 > > anon N0=98304 N1=0 N2=8863514624 N3=4021567488 > > anon N0=98304 N1=0 N2=7789772800 N3=5095309312 > > anon N0=98304 N1=0 N2=6716030976 N3=6169051136 > > anon N0=98304 N1=0 N2=5642289152 N3=7242792960 > > anon N0=98304 N1=0 N2=5105442816 N3=7779639296 > > anon N0=98304 N1=0 N2=5105442816 N3=7779639296 > > anon N0=98304 N1=0 N2=4837007360 N3=8048074752 > > anon N0=98304 N1=0 N2=3763265536 N3=9121816576 > > anon N0=98304 N1=0 N2=2689523712 N3=10195558400 > > anon N0=98304 N1=0 N2=2515148800 N3=10369933312 > > anon N0=98304 N1=0 N2=2515148800 N3=10369933312 > > anon N0=98304 N1=0 N2=2515148800 N3=10369933312 > > anon N0=98304 N1=0 N2=3320455168 N3=9564626944 > > anon N0=98304 N1=0 N2=4394196992 N3=8490885120 > > anon N0=98304 N1=0 N2=5105442816 N3=7779639296 > > anon N0=98304 N1=0 N2=6174195712 N3=6710886400 > > anon N0=98304 N1=0 N2=7247937536 N3=5637144576 > > anon N0=98304 N1=0 N2=8321679360 N3=4563402752 > > anon N0=98304 N1=0 N2=9395421184 N3=3489660928 > > anon N0=98304 N1=0 N2=10247872512 N3=2637209600 > > anon N0=98304 N1=0 N2=10247872512 N3=2637209600 > > > > 2. Root cause: > > Since commit 3e32158767b0 ("mm/mprotect.c: don't touch single threaded > > PTEs which are on the right node")the PTE of local pages will not be > > changed in change_pte_range() for single-threaded process, so no > > page_faults information will be generated in do_numa_page(). If a > > single-threaded process has memory on another node, it will > > unconditionally migrate all of it's local memory to that node, > > even if the remote node has only one page. > > > > So, let's fix it. The memory of single-threaded process should follow > > the cpu, not the numa faults info in order to avoid memory thrashing. > > Show the test results (numa stats) of the fixed kernel? > After a long time of testing, there is no memory thrashing from the beginning. while :;do cat memory.numa_stat | grep -w anon;sleep 5;done anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 anon N0=2548117504 N1=10336903168 N2=139264 N3=0 I will add it to the commit in the next version. > > Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com> > > --- > > kernel/sched/fair.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 24dda708b699..d7cbbda568fb 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -2898,6 +2898,12 @@ static void task_numa_placement(struct task_struct *p) > > numa_group_count_active_nodes(ng); > > spin_unlock_irq(group_lock); > > max_nid = preferred_group_nid(p, max_nid); > > + } else if (atomic_read(&p->mm->mm_users) == 1) { > > + /* > > + * The memory of a single-threaded process should > > + * follow the CPU in order to avoid memory thrashing. > > + */ > > + max_nid = numa_node_id(); > > } > > > > if (max_faults) { > > The change looks reasonable for me, Thanks! > > Acked-by: "Huang, Ying" <ying.huang@intel.com> > Thanks. > -- > Best Regards, > Huang, Ying
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 24dda708b699..d7cbbda568fb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2898,6 +2898,12 @@ static void task_numa_placement(struct task_struct *p) numa_group_count_active_nodes(ng); spin_unlock_irq(group_lock); max_nid = preferred_group_nid(p, max_nid); + } else if (atomic_read(&p->mm->mm_users) == 1) { + /* + * The memory of a single-threaded process should + * follow the CPU in order to avoid memory thrashing. + */ + max_nid = numa_node_id(); } if (max_faults) {
I found a problem in my test machine that the memory of a process is repeatedly migrated between two nodes and does not stop. 1.Test step and the machines. ------------ VM machine: 4 numa nodes and 10GB per node. stress --vm 1 --vm-bytes 12g --vm-keep The info of numa stat: while :;do cat memory.numa_stat | grep -w anon;sleep 5;done anon N0=98304 N1=0 N2=10250747904 N3=2634334208 anon N0=98304 N1=0 N2=10250747904 N3=2634334208 anon N0=98304 N1=0 N2=9937256448 N3=2947825664 anon N0=98304 N1=0 N2=8863514624 N3=4021567488 anon N0=98304 N1=0 N2=7789772800 N3=5095309312 anon N0=98304 N1=0 N2=6716030976 N3=6169051136 anon N0=98304 N1=0 N2=5642289152 N3=7242792960 anon N0=98304 N1=0 N2=5105442816 N3=7779639296 anon N0=98304 N1=0 N2=5105442816 N3=7779639296 anon N0=98304 N1=0 N2=4837007360 N3=8048074752 anon N0=98304 N1=0 N2=3763265536 N3=9121816576 anon N0=98304 N1=0 N2=2689523712 N3=10195558400 anon N0=98304 N1=0 N2=2515148800 N3=10369933312 anon N0=98304 N1=0 N2=2515148800 N3=10369933312 anon N0=98304 N1=0 N2=2515148800 N3=10369933312 anon N0=98304 N1=0 N2=3320455168 N3=9564626944 anon N0=98304 N1=0 N2=4394196992 N3=8490885120 anon N0=98304 N1=0 N2=5105442816 N3=7779639296 anon N0=98304 N1=0 N2=6174195712 N3=6710886400 anon N0=98304 N1=0 N2=7247937536 N3=5637144576 anon N0=98304 N1=0 N2=8321679360 N3=4563402752 anon N0=98304 N1=0 N2=9395421184 N3=3489660928 anon N0=98304 N1=0 N2=10247872512 N3=2637209600 anon N0=98304 N1=0 N2=10247872512 N3=2637209600 2. Root cause: Since commit 3e32158767b0 ("mm/mprotect.c: don't touch single threaded PTEs which are on the right node")the PTE of local pages will not be changed in change_pte_range() for single-threaded process, so no page_faults information will be generated in do_numa_page(). If a single-threaded process has memory on another node, it will unconditionally migrate all of it's local memory to that node, even if the remote node has only one page. So, let's fix it. The memory of single-threaded process should follow the cpu, not the numa faults info in order to avoid memory thrashing. Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com> --- kernel/sched/fair.c | 6 ++++++ 1 file changed, 6 insertions(+)