Messages in this thread Patch in this message | | | Date | Tue, 14 Jul 2015 14:07:08 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2] mm: show proportional swap share of the mapping |
| |
On Mon, 15 Jun 2015 22:06:54 +0900 Minchan Kim <minchan@kernel.org> wrote:
> We want to know per-process workingset size for smart memory management > on userland and we use swap(ex, zram) heavily to maximize memory efficiency > so workingset includes swap as well as RSS. > > On such system, if there are lots of shared anonymous pages, it's > really hard to figure out exactly how many each process consumes > memory(ie, rss + wap) if the system has lots of shared anonymous > memory(e.g, android). > > This patch introduces SwapPss field on /proc/<pid>/smaps so we can get > more exact workingset size per process. > > ... > > +int swp_swapcount(swp_entry_t entry) > +{ > + int count, tmp_count, n; > + struct swap_info_struct *p; > + struct page *page; > + pgoff_t offset; > + unsigned char *map; > + > + p = swap_info_get(entry); > + if (!p) > + return 0; > + > + count = swap_count(p->swap_map[swp_offset(entry)]); > + if (!(count & COUNT_CONTINUED)) > + goto out; > + > + count &= ~COUNT_CONTINUED; > + n = SWAP_MAP_MAX + 1; > + > + offset = swp_offset(entry); > + page = vmalloc_to_page(p->swap_map + offset); > + offset &= ~PAGE_MASK; > + VM_BUG_ON(page_private(page) != SWP_CONTINUED); > + > + do { > + page = list_entry(page->lru.next, struct page, lru); > + map = kmap_atomic(page) + offset; > + tmp_count = *map; > + kunmap_atomic(map);
A little thing: I've never liked the way that kunmap_atomic() accepts any address within the page. It's weird, and it makes the reviewer have to scramble around to make sure the offset can never be >= PAGE_SIZE.
We can easily avoid doing it here:
--- a/mm/swapfile.c~mm-show-proportional-swap-share-of-the-mapping-fix +++ a/mm/swapfile.c @@ -904,8 +904,8 @@ int swp_swapcount(swp_entry_t entry) do { page = list_entry(page->lru.next, struct page, lru); - map = kmap_atomic(page) + offset; - tmp_count = *map; + map = kmap_atomic(page); + tmp_count = map[offset]; kunmap_atomic(map); count += (tmp_count & ~COUNT_CONTINUED) * n; > + count += (tmp_count & ~COUNT_CONTINUED) * n; > + n *= (SWAP_CONT_MAX + 1); > + } while (tmp_count & COUNT_CONTINUED); > +out: > + spin_unlock(&p->lock); > + return count; > +} > > ... >
| |