On Mon 20-11-17 16:51:10, Andrew Morton wrote: > On Wed, 15 Nov 2017 23:14:09 +0000 Roman Gushchin <[email protected]> wrote: > > > Currently we display some hugepage statistics (total, free, etc) > > in /proc/meminfo, but only for default hugepage size (e.g. 2Mb). > > > > If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64), > > /proc/meminfo output can be confusing, as non-default sized hugepages > > are not reflected at all, and there are no signs that they are > > existing and consuming system memory. > > > > To solve this problem, let's display the total amount of memory, > > consumed by hugetlb pages of all sized (both free and used). > > Let's call it "Hugetlb", and display size in kB to match generic > > /proc/meminfo style. > > > > For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated): > > $ cat /proc/meminfo > > MemTotal: 8168984 kB > > MemFree: 3789276 kB > > <...> > > CmaFree: 0 kB > > HugePages_Total: 1024 > > HugePages_Free: 1024 > > HugePages_Rsvd: 0 > > HugePages_Surp: 0 > > Hugepagesize: 2048 kB > > Hugetlb: 4194304 kB > > DirectMap4k: 32632 kB > > DirectMap2M: 4161536 kB > > DirectMap1G: 6291456 kB > > > > Also, this patch updates corresponding docs to reflect > > Hugetlb entry meaning and difference between Hugetlb and > > HugePages_Total * Hugepagesize. > > > > ... > > > > --- a/mm/hugetlb.c > > +++ b/mm/hugetlb.c > > @@ -2973,20 +2973,32 @@ int hugetlb_overcommit_handler(struct ctl_table > > *table, int write, > > > > void hugetlb_report_meminfo(struct seq_file *m) > > { > > - struct hstate *h = &default_hstate; > > + struct hstate *h; > > + unsigned long total = 0; > > + > > if (!hugepages_supported()) > > return; > > - seq_printf(m, > > - "HugePages_Total: %5lu\n" > > - "HugePages_Free: %5lu\n" > > - "HugePages_Rsvd: %5lu\n" > > - "HugePages_Surp: %5lu\n" > > - "Hugepagesize: %8lu kB\n", > > - h->nr_huge_pages, > > - h->free_huge_pages, > > - h->resv_huge_pages, > > - h->surplus_huge_pages, > > - 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); > > + > > + for_each_hstate(h) { > > + unsigned long count = h->nr_huge_pages; > > + > > + total += (PAGE_SIZE << huge_page_order(h)) * count; > > + > > + if (h == &default_hstate) > > I'm not understanding this test. Are we assuming that default_hstate > always refers to the highest-index hstate? If so why, and is that > valid?
The whole point of this checks is to provide hugetlb detailed stats _only_ for the default hstate because that is what we have been doing traditionally. The loop is there only to gather total amount and display it separately. > > + seq_printf(m, > > + "HugePages_Total: %5lu\n" > > + "HugePages_Free: %5lu\n" > > + "HugePages_Rsvd: %5lu\n" > > + "HugePages_Surp: %5lu\n" > > + "Hugepagesize: %8lu kB\n", > > + count, > > + h->free_huge_pages, > > + h->resv_huge_pages, > > + h->surplus_huge_pages, > > + (PAGE_SIZE << huge_page_order(h)) / 1024); > > + } > > + > > + seq_printf(m, "Hugetlb: %8lu kB\n", total / 1024); > > } > -- Michal Hocko SUSE Labs
