* Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:
> > @@ -43,11 +44,19 @@ static int full_paths;
> > static unsigned long page_size;
> > static unsigned long mmap_window = 32;
> >
> > +struct ip_chain_event {
> > + __u16 nr;
>
> Is it needed to have the nr encoded in the ip_chain? We can
> already find it by doing kernel + user.
That's a good observation. Since we havent exposed the call-chain
bits in upstream version of the tools, we could still improve on
this a little bit.
I think the best would be context separators which occupy a special
address in some quiet corner of the 64-bit address space.
That way we'd have streams of u64 entries:
ip-1
ip-2
CONTEXT_IRQ
ip-3
ip-4
CONTEXT_SYSCALL
ip-5
ip-6
The following contexts IDs would be useful:
CONTEXT_NMI
CONTEXT_HARDIRQ
CONTEXT_SOFTIRQ
CONTEXT_KERNEL
CONTEXT_USER
CONTEXT_GUEST_NMI
CONTEXT_GUEST_HARDIRQ
CONTEXT_GUEST_SOFTIRQ
CONTEXT_GUEST_KERNEL
CONTEXT_GUEST_USER
The context IDs would occupy some rare and
unlikely-to-be-allocated-soon corner of the address space - say
startig at 0x8765432112345000. (and real RIPs would be filtered and
nudged just outside that space of a handful IDs.)
The advantage would be that this is infinitely flexible and
extensible - any level of nesting can be expressed without having
separate fields for nr_hv_guest_irq, etc. It's also pretty fast to
parse.
Hm?
Ingo
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