Messages in this thread | | | Subject | Re: [PATCH V2] sched: Improve load balancing in the presence of idle CPUs | From | Jason Low <> | Date | Thu, 26 Mar 2015 22:01:12 -0700 |
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On Fri, 2015-03-27 at 10:03 +0530, Preeti U Murthy wrote: > Hi Wanpeng > > On 03/27/2015 07:42 AM, Wanpeng Li wrote: > > Hi Preeti, > > On Thu, Mar 26, 2015 at 06:32:44PM +0530, Preeti U Murthy wrote: > >> > >> 1. An ILB CPU was chosen from the first numa domain to trigger nohz idle > >> load balancing [Given the experiment, upto 6 CPUs per core could be > >> potentially idle in this domain.] > >> > >> 2. However the ILB CPU would call load_balance() on itself before > >> initiating nohz idle load balancing. > >> > >> 3. Given cores are SMT8, the ILB CPU had enough opportunities to pull > >> tasks from its sibling cores to even out load. > >> > >> 4. Now that the ILB CPU was no longer idle, it would abort nohz idle > >> load balancing > > > > I don't see abort nohz idle load balancing when ILB CPU was no longer idle > > in nohz_idle_balance(), could you explain more in details? > > When the ILB CPU pulls load in rebalance_domains(), its idle state > is set to CPU_NOT_IDLE. > > "" > idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
Hi Preeti,
The "idle" variable is a local variable to the rebalance_domains() function. In that case, that shouldn't have an affect on the idle value that gets passed to nohz_idle_balance().
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