Re: perfmon trouble

From: Matthew Wilcox
Date: Mon Jun 11 2018 - 13:18:20 EST

On Mon, Jun 11, 2018 at 10:04:00AM -0700, Linus Torvalds wrote:
> On Mon, Jun 11, 2018 at 9:49 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> >
> > The problem is that even oprofile on ia64 depends on perfmon.
> Hmm? You can definitely enable ia64 support for oprofile even without perfmon.

Oh, I think my memory is playing tricks on me. This is my confusion, I think:

oprofile-$(CONFIG_PERFMON) += perfmon.o

so perfmon events are exposed through oprofile, but you can disable
perfmon without disabling oprofile.

> Because I'd be inclined to just remove CONFIG_PERFMON support, and see
> if anybody even notices..
> I'm not expecting a lot of people to do a lot of oprofile on ia64
> anyway. It's a bit late to start optimizing things now.
> Do people use perfmon still? Maybe. Maybe not. Perhaps we could just
> mark it as broken in the Kconfig file for now, and see if somebody
> says something?

That gets my vote.

Tony? Fenghua?

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 792437d526c6..ff861420b8f5 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -455,6 +455,7 @@ config IA64_MCA_RECOVERY

config PERFMON
bool "Performance monitor support"
+ depends on BROKEN
Selects whether support for the IA-64 performance monitor hardware
is included in the kernel. This makes some kernel data-structures a