Re: [PATCH v2] x86: don't ever patch back to UP if we unplug cpus.

2012-08-22 Thread Rusty Russell
On Wed, 22 Aug 2012 11:41:53 +0200, Ingo Molnar wrote: > > * Rusty Russell wrote: > > > We still patch SMP instructions to UP variants if we boot with a > > single CPU, but not at any other time. In particular, not if we > > unplug CPUs to return to a single cpu. > > > > Paul McKenney points

Re: [PATCH v2] x86: don't ever patch back to UP if we unplug cpus.

2012-08-22 Thread Ingo Molnar
* Rusty Russell wrote: > We still patch SMP instructions to UP variants if we boot with a > single CPU, but not at any other time. In particular, not if we > unplug CPUs to return to a single cpu. > > Paul McKenney points out: > > mean offline overhead is 6251/48=130.2 milliseconds. > > If

Re: [PATCH v2] x86: don't ever patch back to UP if we unplug cpus.

2012-07-30 Thread Suresh Siddha
On Mon, 2012-07-30 at 11:40 +0930, Rusty Russell wrote: > We still patch SMP instructions to UP variants if we boot with a > single CPU, but not at any other time. In particular, not if we > unplug CPUs to return to a single cpu. > > Paul McKenney points out: > > mean offline overhead is 6251/4

[PATCH v2] x86: don't ever patch back to UP if we unplug cpus.

2012-07-29 Thread Rusty Russell
We still patch SMP instructions to UP variants if we boot with a single CPU, but not at any other time. In particular, not if we unplug CPUs to return to a single cpu. Paul McKenney points out: mean offline overhead is 6251/48=130.2 milliseconds. If I remove the alternatives_smp_switch() from