lkml.org 
[lkml]   [2020]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: thp: don't need drain lru cache when splitting and mlocking THP
On Thu, Apr 02, 2020 at 04:37:06PM -0700, Yang Shi wrote:
>
>
> 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.

Ah, that's right! The checks in swap.c are for PageCompound.

\
 
 \ /
  Last update: 2020-04-03 15:13    [W:2.140 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site