Re: mailing list for trace users

From: Peter Zijlstra
Date: Tue Sep 22 2009 - 07:00:07 EST


On Tue, 2009-09-22 at 12:13 +0300, Avi Kivity wrote:
>
> Yes please. Here's a question to start it off - how to I 'perf
> annotate' a symbol in a module?
>
> $ perf report
> # Samples: 68202
> #
> # Overhead Command Shared Object Symbol
> # ........ ............... ............. ......
> #
> 84.17% qemu-system-x86 [kernel] [k] vmx_vcpu_run
> [kvm_intel]
> 4.28% qemu-system-x86 [kernel] [k]
> kvm_arch_vcpu_ioctl_run
> [kvm]
> 0.88% qemu-system-x86 [kernel] [k] add_preempt_count
> 0.75% qemu-system-x86 [kernel] [k]
> _spin_unlock_irqrestore
> 0.68% qemu-system-x86 [kernel] [k] _spin_lock_irq
>
> $ perf annotate -k ~avi/kvm/linux-2.6/vmlinux -m vmx_vcpu_run
> Error: symbol 'vmx_vcpu_run' not present amongst the samples.
>
> builtin symbols work.

We need a /proc/modules parser that then also locates and loads .ko
files which aren't stripped.

I think Mike played around with that a bit.

The typical problem is that people use 'make INSTALL_MOD_STRIP=1
modules_install' to install their modules, because otherwise the initrd
thingies explode, the side effect is that the !initrd modules are
stripped too.

Ideally initrd tools should strip whatever they stick in. Then again,
ideally we'd not have any initrd and modules crap to begin with ;-)

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