[lkml]   [2007]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Linux 2.6.21-rc5

On Wed, 28 Mar 2007, Andi Kleen wrote:
> Can you test this patch please?

This patch is totally broken.

> i386/x86-64: Convert nmi reservation to be global
> It doesn't make much sense to have this per CPU, because all
> the services using NMIs run on all CPUs. So make it global.


If you do this, then you must make all *callers* be global too. But they
aren't. Right now all callers do per-CPU setup!

See for example enable_lapic_nmi_watchdog():

on_each_cpu(setup_apic_nmi_watchdog, NULL, 0, 1);

where "setup_apic_nmi_watchdog()" will call "setup_k7_watchdog()", which
in turn will do a per-CPU reservation of the perfctl for the watchdog.

So I agree in that it probably doesn't make sense to have NMI/perfctl
reservation per-CPU, but you can't just change the reservation and ignore
all the *users* of that reservation that assumed that it was per-CPU.

Is that code insane? Probably. But it probably also works. After your
patch, one CPU will be able to reserve the NMI/perfctl thing (fine so far)
but then all the other CPU's that try to do it will fail.

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: 2007-03-28 19:59    [W:0.109 / U:2.924 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site