Re: [mm/mremap] ecf8443e51: vm-scalability.throughput -29.4% regression
flat view
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: 2021-06-14 14:59:57
Also in:
linux-mm, lkml, oe-lkp
On Mon, Jun 14, 2021 at 7:39 AM kernel test robot [off-list ref] wrote:
FYI, we noticed a -29.4% regression of vm-scalability.throughput due to commit:
ecf8443e51a8 ("[PATCH v7 02/11] mm/mremap: Fix race between MOVE_PUD mremap and pageout")
Ouch.
I guess it's not a huge surprise, but that's a fairly large regression.
Probably because the pud lock is just one single lock ("No scalability
reason to split PUD locks yet").
What happens if pud_lockptr() were to do the same thing that pmd_lockptr() does?
Linus