[lkml]   [2007]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC] Patch: dynticks: idle load balancing
On Tue, Jan 30, 2007 at 01:57:09PM -0800, Siddha, Suresh B wrote:
> Please let me know if you still see this issue with the latest -rt kernel.
> On Tue, Jan 16, 2007 at 12:35:05PM +0100, Ingo Molnar wrote:
> > on the latest -rt kernel, when the dynticks load-balancer is enabled,
> > then a dual-core Core2 Duo test-system increases its irq rate from the
> > normal 15/17 per second to 300-400/sec - on a completely idle system(!).
> > Any idea what's going on? I'll disable the load balancer for now.

Ok. got time to look into this.

The answer is simple. load_balancing in the recent kernels is happening
using SCHED_SOFTIRQ and in -rt tree that happens not in the idle process
context but in the context of softirqd for SCHED_SOFTIRQ.

This breaks the dynticks load balancer and also the regular idle load balancing
too :(

Am on to fixing the problem now :)

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-02-07 23:55    [W:0.122 / U:0.856 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site