[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: [PATCH] migration: Move bitmap_mutex out of migration_bitmap_clear_d

From: Wang, Wei W
Subject: RE: [PATCH] migration: Move bitmap_mutex out of migration_bitmap_clear_dirty()
Date: Fri, 2 Jul 2021 02:48:13 +0000

On Thursday, July 1, 2021 10:22 PM, David Hildenbrand wrote:
> On 01.07.21 14:51, Peter Xu wrote:
> Spoiler alert: the introduction of clean bitmaps partially broke free page 
> hinting
> already (as clearing happens deferred -- and might never happen if we don't
> migrate *any* page within a clean bitmap chunk, so pages actually remain
> dirty ...). "broke" here means that pages still get migrated even though they
> were reported by the guest. We'd actually not want to use clean bmaps with 
> free
> page hinting ... long story short, free page hinting is a very fragile beast 
> already
> and some of the hints are basically ignored and pure overhead ...

Not really. Both clear_bmap and free page hint are to "clear" the bitmap.
No matter who comes first to clear it, it won’t cause more (unexpected) pages 
to be sent.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]