lkml.org 
[lkml]   [2002]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] 2.5.21 Nonlinear CPU support
Andrew Morton wrote:
>
> Rusty Russell wrote:
> >
> > ...
> > Let's not perpetuate the myth that everything in the kernel needs to
> > be tuned to the last cycle at all costs, hm?
>
> I was more concerned about the RAM use, actually.
>
> This patch is an additional reason for CONFIG_NR_CPUS, but I've rather
> gone cold on that idea because the "proper fix" is to make all those
> huge per-cpu arrays dynamically allocated. So you can run a 64p kernel
> on 2p without losing hundreds of k of memory and kernel address space.
>
> But it looks like all those dynamically-allocated structures would
> have to be allocated out to NR_CPUS anyway, to support hotplug, yes?
>
> In which case, CONFIG_NR_CPUS is the only way to get the memory
> back...

Re-allocation of tables when adding CPUs is another
option. That means the data moves - so others have to store
array indices instead of direct pointers to stuff they use.
Dynamic allocation not merely at boottime, but everytime.

Adding a CPU becomes more expensive, but that won't
happen hundreds of times a second anyway.

Helge Hafting
-
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: 2005-03-22 13:26    [W:0.194 / U:0.500 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site