Messages in this thread |  | | Subject | Re: [PATCH] mm: thp: don't need drain lru cache when splitting and mlocking THP | From | Yang Shi <> | Date | Thu, 2 Apr 2020 16:37:06 -0700 |
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On 4/2/20 4:17 PM, Daniel Jordan wrote: > On Thu, Apr 02, 2020 at 07:04:11PM -0400, Daniel Jordan wrote: >> On Sat, Mar 28, 2020 at 03:29:40AM +0800, Yang Shi wrote: >>> Since the commit 8f182270dfec ("mm/swap.c: flush lru pvecs on compound >>> page arrival") THP would not stay in pagevec anymore. So the >>> optimization made by commit d965432234db ("thp: increase >>> split_huge_page() success rate") doesn't make sense anymore, which tries >>> to unpin munlocked THPs from pagevec by draining pagevec. >>> >>> And draining lru cache before isolating THP in mlock path is unnecessary >>> either. >> Can we get some of that nice history in this part too? >> >> Draining lru cache before isolating THP in mlock path is also unnecessary. >> b676b293fb48 ("mm, thp: fix mapped pages avoiding unevictable list on mlock") >> added it and 9a73f61bdb8a ("thp, mlock: do not mlock PTE-mapped file huge >> pages") accidentally carried it over after the above optimization went in. >> >>> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> >>> Cc: Hugh Dickins <hughd@google.com> >>> Cc: Andrea Arcangeli <aarcange@redhat.com> >>> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> >> Since we don't mlock pte-mapped THP, it seems these huge pages wouldn't ever be >> in the pagevecs if I'm understanding it all. > Actually pte-mapped THP doesn't matter for this, both paths always drain when > they're working with pmd-mapped THP.
Actually either pte-mapped or pmd-mapped doesn't matter, as long as it is compound page the lru cache would be flushed immediately upon the arrival of the compound page.
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