On 6 January 2014 17:31, Peter Zijlstra peterz@infradead.org wrote:
On Mon, Jan 06, 2014 at 02:41:31PM +0100, Vincent Guittot wrote:
IMHO, these settings will disappear sooner or later, as an example the idle/busy _idx are going to be removed by Alex's patch.
Well I'm still entirely unconvinced by them..
removing the cpu_load array makes sense, but I'm starting to doubt the removal of the _idx things.. I think we want to retain them in some form, it simply makes sense to look at longer term averages when looking at larger CPU groups.
So maybe we can express the things in log_2(group-span) or so, but we need a working replacement for the cpu_load array. Ideally some expression involving the blocked load.
Using the blocked load can surely give benefit in the load balance because it gives a view of potential load on a core but it still decay with the same speed than runnable load average so it doesn't solve the issue for longer term average. One way is to have a runnable average load with longer time window
Its another one of those things I need to ponder more :-)