From: Stefan Roesch Date: Tue, 26 Sep 2023 04:09:37 +0000 (-0700) Subject: mm/ksm: add pages_skipped metric X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e5a68991268906a6989f1bf273580c2218662ad6;p=linux.git mm/ksm: add pages_skipped metric This change adds the "pages skipped" metric. To be able to evaluate how successful smart page scanning is, the pages skipped metric can be compared to the pages scanned metric. The pages skipped metric is a cumulative counter. The counter is stored under /sys/kernel/mm/ksm/pages_skipped. Link: https://lkml.kernel.org/r/20230926040939.516161-3-shr@devkernel.io Signed-off-by: Stefan Roesch Reviewed-by: David Hildenbrand Cc: Johannes Weiner Cc: Rik van Riel Signed-off-by: Andrew Morton --- diff --git a/mm/ksm.c b/mm/ksm.c index 8ad66b1c91b9d..7efcc68ccc6ea 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -294,6 +294,9 @@ static bool ksm_smart_scan = true; /* The number of zero pages which is placed by KSM */ unsigned long ksm_zero_pages; +/* The number of pages that have been skipped due to "smart scanning" */ +static unsigned long ksm_pages_skipped; + #ifdef CONFIG_NUMA /* Zeroed when merging across nodes is not allowed */ static unsigned int ksm_merge_across_nodes = 1; @@ -2377,6 +2380,7 @@ static bool should_skip_rmap_item(struct page *page, } /* Skip this page */ + ksm_pages_skipped++; rmap_item->remaining_skips--; remove_rmap_item_from_tree(rmap_item); return true; @@ -3464,6 +3468,13 @@ static ssize_t pages_volatile_show(struct kobject *kobj, } KSM_ATTR_RO(pages_volatile); +static ssize_t pages_skipped_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%lu\n", ksm_pages_skipped); +} +KSM_ATTR_RO(pages_skipped); + static ssize_t ksm_zero_pages_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { @@ -3561,6 +3572,7 @@ static struct attribute *ksm_attrs[] = { &pages_sharing_attr.attr, &pages_unshared_attr.attr, &pages_volatile_attr.attr, + &pages_skipped_attr.attr, &ksm_zero_pages_attr.attr, &full_scans_attr.attr, #ifdef CONFIG_NUMA