From ea426c2a7de8e575108b7cecd3374e0c15a9f25e Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 6 Aug 2020 23:20:35 -0700 Subject: mm: memcg: prepare for byte-sized vmstat items To implement per-object slab memory accounting, we need to convert slab vmstat counters to bytes. Actually, out of 4 levels of counters: global, per-node, per-memcg and per-lruvec only two last levels will require byte-sized counters. It's because global and per-node counters will be counting the number of slab pages, and per-memcg and per-lruvec will be counting the amount of memory taken by charged slab objects. Converting all vmstat counters to bytes or even all slab counters to bytes would introduce an additional overhead. So instead let's store global and per-node counters in pages, and memcg and lruvec counters in bytes. To make the API clean all access helpers (both on the read and write sides) are dealing with bytes. To avoid back-and-forth conversions a new flavor of read-side helpers is introduced, which always returns values in pages: node_page_state_pages() and global_node_page_state_pages(). Actually new helpers are just reading raw values. Old helpers are simple wrappers, which will complain on an attempt to read byte value, because at the moment no one actually needs bytes. Thanks to Johannes Weiner for the idea of having the byte-sized API on top of the page-sized internal storage. Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Acked-by: Johannes Weiner Cc: Christoph Lameter Cc: Michal Hocko Cc: Tejun Heo Link: http://lkml.kernel.org/r/20200623174037.3951353-3-guro@fb.com Signed-off-by: Linus Torvalds --- drivers/base/node.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/base') diff --git a/drivers/base/node.c b/drivers/base/node.c index 5b02f69769e8..e21e31359297 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -513,7 +513,7 @@ 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", node_stat_name(i), - node_page_state(pgdat, i)); + node_page_state_pages(pgdat, i)); return n; } -- cgit v1.2.3