在 2021/2/24 下午4:37, Yu Zhao 写道:
>>> @@ -65,18 +63,12 @@ static __always_inline void __clear_page_lru_flags(struct page *page)
>>> */
>>> static __always_inline enum lru_list page_lru(struct page *page)
>>> {
>>> - enum lru_list lru;
>>> + unsigned long flags = READ_ONCE(page->flags);
>>>
>>> VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
>>>
>>> - if (PageUnevictable(page))
>>> - return LRU_UNEVICTABLE;
>>> -
>>> - lru = page_is_file_lru(page) ? LRU_INACTIVE_FILE : LRU_INACTIVE_ANON;
>>> - if (PageActive(page))
>>> - lru += LRU_ACTIVE;
>>> -
>>> - return lru;
>>> + return (flags & BIT(PG_unevictable)) ? LRU_UNEVICTABLE :
>>> + (LRU_FILE * !(flags & BIT(PG_swapbacked)) + !!(flags & BIT(PG_active)));
>> Currently each of page flags used different flags policy, does this mean above flags could be
>> change to PF_ANY policy?
> That's a good question. Semantically, no because
> PG_{active,unevictable} only apply to head pages. But practically,
> I think the answer is yes, and the only place that needs to
> explicitly call compound_head() is gather_stats() in
> fs/proc/task_mmu.c, IIRC.
>
A quick testing for your testing request:
# ll vmlinux vmlinux.new
-rwxr-xr-x 1 root root 62245304 Feb 24 16:57 vmlinux
-rwxr-xr-x 1 root root 62245280 Feb 24 16:55 vmlinux.new
# gcc --version
gcc (GCC) 8.3.1 20190311 (Red Hat 8.3.1-3)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# scripts/bloat-o-meter vmlinux vmlinux.new
add/remove: 0/0 grow/shrink: 1/15 up/down: 1/-2008 (-2007)
Function old new delta
vermagic 37 38 +1
trace_event_raw_event_mm_lru_insertion 471 418 -53
perf_trace_mm_lru_insertion 526 473 -53
__munlock_pagevec 1134 1069 -65
isolate_migratepages_block 2623 2547 -76
isolate_lru_page 384 303 -81
__pagevec_lru_add 753 652 -101
release_pages 780 667 -113
__page_cache_release 429 276 -153
move_pages_to_lru 871 702 -169
lru_lazyfree_fn 712 539 -173
check_move_unevictable_pages 938 763 -175
__activate_page 665 488 -177
lru_deactivate_fn 636 452 -184
pagevec_move_tail_fn 597 411 -186
lru_deactivate_file_fn 1000 751 -249
Total: Before=17029652, After=17027645, chg -0.01%
