On Thu 16-11-17 21:48:05, Byungchul Park wrote:

On 11/16/2017 9:02 PM, Michal Hocko wrote:

quoted

for each struct page. So you are doubling the size. Who is going to
enable this config option? You are moving this to page_ext in a later
patch which is a good step but it doesn't go far enough because this
still consumes those resources. Is there any problem to make this
kernel command line controllable? Something we do for page_owner for
example?

Sure. I will add it.

quoted

Also it would be really great if you could give us some measures about
the runtime overhead. I do not expect it to be very large but this is

The major overhead would come from the amount of additional memory
consumption for 'lockdep_map's.

yes

Do you want me to measure the overhead by the additional memory
consumption?

Or do you expect another overhead?

I would be also interested how much impact this has on performance. I do
not expect it would be too large but having some numbers for cache cold
parallel kbuild or other heavy page lock workloads.
-- 
Michal Hocko
SUSE Labs