lkml.org 
[lkml]   [2017]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 0/5] mm: support parallel free of memory
On Fri, Mar 17, 2017 at 08:47:08AM +0100, Michal Hocko wrote:
> On Thu 16-03-17 11:36:21, Tim Chen wrote:
> [...]
> > Perhaps we can only do this expedited exit only when there are idle cpus around.
> > We can use the root sched domain's overload indicator for such a quick check.
>
> This is not so easy, I am afraid. Those CPUs might be idle for a good
> reason (power saving etc.). You will never know by simply checking
> one metric. This is why doing these optimistic parallelization
> optimizations is far from trivial. This is not the first time somebody
> wants to do this. People are trying to make THP migration faster
> doing the similar thing. I guess we really need a help from the
> scheduler to do this properly, though. I've been thinking about an API
> (e.g. try_to_run_in_backgroun) which would evaluate all these nasty
> details and either return with -EBUSY or kick the background thread to
> accomplish the work if the system is reasonably idle. I am not really
> sure whether such an API is viable though.

> Peter, what do you think?

Much pain lies this way.

Also, -enocontext.

\
 
 \ /
  Last update: 2017-03-17 13:54    [W:0.110 / U:1.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site