lkml.org 
[lkml]   [2007]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [patch 5/8] Immediate Values - x86 Optimization (simplified)
Date
On Tuesday 20 November 2007 01:28:03 Mathieu Desnoyers wrote:
> * Rusty Russell (rusty@rustcorp.com.au) wrote:
> > I think it would be easier to just fast-path the num_online_cpus == 1
> > case, even if you want to keep this "update_early" interface.
>
> Nope, that could lead to problems. I call core_immediate_update()
> _very_ early, before boot_cpu_init() is called.

Ah, I see the problem. It would in fact be clearer for us to move
boot_cpu_init() up to just after smp_setup_processor_id() in start_kernel
anyway, not just for this code, but in general.

> Therefore,
> cpu_online_map is not set yet. I am not sure the benefit of using
> num_online_cpus outweights the added fragility wrt other boot process
> initializations.

I think it's still a win, though worth a comment that we always go via the
non-IPI path for the early boot case.

Cheers,
Rusty.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-11-20 00:09    [W:0.072 / U:0.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site