Re: [PATCH 0/6] migration/postcopy: enable compress during postcopy

[Dr. David Alan Gilbert]

* Wei Yang (address@hidden) wrote:
> This patch set tries enable compress during postcopy.
> 
> postcopy requires to place a whole host page, while migration thread migrate
> memory in target page size. This makes postcopy need to collect all target
> pages in one host page before placing via userfaultfd.
> 
> To enable compress during postcopy, there are two problems to solve:
> 
>     1. Random order for target page arrival
>     2. Target pages in one host page arrives without interrupt by target
>        page from other host page
> 
> The first one is handled by counting the number of target pages arrived
> instead of the last target page arrived.
> 
> The second one is handled by:
> 
>     1. Flush compress thread for each host page
>     2. Wait for decompress thread for before placing host page
> 
> With the combination of these two changes, compress is enabled during
> postcopy.

What have you tested this with? 2MB huge pages I guess?

Dave

> Wei Yang (6):
>   migration/postcopy: reduce memset when it is zero page and
>     matches_target_page_size
>   migration/postcopy: wait for decompress thread in precopy
>   migration/postcopy: count target page number to decide the
>     place_needed
>   migration/postcopy: set all_zero to true on the first target page
>   migration/postcopy: enable random order target page arrival
>   migration/postcopy: enable compress during postcopy
> 
>  migration/migration.c | 11 --------
>  migration/ram.c       | 65 ++++++++++++++++++++++++++++++-------------
>  2 files changed, 45 insertions(+), 31 deletions(-)
> 
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK