On Tue 19-12-17 14:39:25, Kemi Wang wrote: > To avoid deviation, this patch uses node_page_state_snapshot instead of > node_page_state for node page stats query. > e.g. cat /proc/zoneinfo > cat /sys/devices/system/node/node*/vmstat > cat /sys/devices/system/node/node*/numastat > > As it is a slow path and would not be read frequently, I would worry about > it.
The changelog doesn't explain why these counters needs any special treatment. _snapshot variants where used only for internal handling where the precision really mattered. We do not have any in-tree user and Jack has removed this by http://lkml.kernel.org/r/20171122094416.26019-1-j...@suse.cz which is already sitting in the mmotm tree. We can re-add it but that would really require a _very good_ reason. > Signed-off-by: Kemi Wang <kemi.w...@intel.com> > --- > drivers/base/node.c | 17 ++++++++++------- > mm/vmstat.c | 2 +- > 2 files changed, 11 insertions(+), 8 deletions(-) > > diff --git a/drivers/base/node.c b/drivers/base/node.c > index a045ea1..cf303f8 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -169,12 +169,15 @@ static ssize_t node_read_numastat(struct device *dev, > "interleave_hit %lu\n" > "local_node %lu\n" > "other_node %lu\n", > - node_page_state(NODE_DATA(dev->id), NUMA_HIT), > - node_page_state(NODE_DATA(dev->id), NUMA_MISS), > - node_page_state(NODE_DATA(dev->id), NUMA_FOREIGN), > - node_page_state(NODE_DATA(dev->id), NUMA_INTERLEAVE_HIT), > - node_page_state(NODE_DATA(dev->id), NUMA_LOCAL), > - node_page_state(NODE_DATA(dev->id), NUMA_OTHER)); > + node_page_state_snapshot(NODE_DATA(dev->id), NUMA_HIT), > + node_page_state_snapshot(NODE_DATA(dev->id), NUMA_MISS), > + node_page_state_snapshot(NODE_DATA(dev->id), > + NUMA_FOREIGN), > + node_page_state_snapshot(NODE_DATA(dev->id), > + NUMA_INTERLEAVE_HIT), > + node_page_state_snapshot(NODE_DATA(dev->id), NUMA_LOCAL), > + node_page_state_snapshot(NODE_DATA(dev->id), > + NUMA_OTHER)); > } > > static DEVICE_ATTR(numastat, S_IRUGO, node_read_numastat, NULL); > @@ -194,7 +197,7 @@ static ssize_t node_read_vmstat(struct device *dev, > for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) > n += sprintf(buf+n, "%s %lu\n", > vmstat_text[i + NR_VM_ZONE_STAT_ITEMS], > - node_page_state(pgdat, i)); > + node_page_state_snapshot(pgdat, i)); > > return n; > } > diff --git a/mm/vmstat.c b/mm/vmstat.c > index 64e08ae..d65f28d 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -1466,7 +1466,7 @@ static void zoneinfo_show_print(struct seq_file *m, > pg_data_t *pgdat, > for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) { > seq_printf(m, "\n %-12s %lu", > vmstat_text[i + NR_VM_ZONE_STAT_ITEMS], > - node_page_state(pgdat, i)); > + node_page_state_snapshot(pgdat, i)); > } > } > seq_printf(m, > -- > 2.7.4 > -- Michal Hocko SUSE Labs
