Messages in this thread Patch in this message | | | Date | Mon, 5 Nov 2018 16:36:15 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 1/5] perf tools: Add fallback functions for cases where cpumode is insufficient |
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Em Mon, Nov 05, 2018 at 07:21:44PM +0000, Hunter, Adrian escreveu: > > In Monday, November 5, 2018 7:30 PM, Arnaldo Carvalho de Melo wrote <SNIP> > > > +struct map *thread__find_map_fallback(struct thread *thread, u8 > > cpumode, > > > + u64 addr, struct addr_location *al) {
> > You named one as _fallback...
> > > + struct map *map = thread__find_map(thread, cpumode, addr, al); > > > + struct machine *machine = thread->mg->machine; > > > + u8 addr_cpumode = machine__addr_cpumode(machine, cpumode, > > addr); > > > + > > > + if (map || addr_cpumode == cpumode) > > > + return map; > > > + > > > + return thread__find_map(thread, addr_cpumode, addr, al); } > > > + > > > struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode, > > > u64 addr, struct addr_location *al) { @@ - > > 1585,6 +1603,15 @@ > > > struct symbol *thread__find_symbol(struct thread *thread, u8 cpumode, > > > return al->sym; > > > }
> > > +struct symbol *thread__find_symbol_fb(struct thread *thread, u8 > > cpumode, > > > + u64 addr, struct addr_location *al)
> > ... and the other as _fb, make it consistent, please.
> ok
> > > +{ > > > + al->sym = NULL; > > > + if (thread__find_map_fallback(thread, cpumode, addr, al)) > > > + al->sym = map__find_symbol(al->map, al->addr); > > > + return al->sym; > > > +}
> > > /* > > > * Callers need to drop the reference to al->thread, obtained in > > > * machine__findnew_thread() > > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > > > index 111ae858cbcb..04edc0eac376 100644 > > > --- a/tools/perf/util/machine.c > > > +++ b/tools/perf/util/machine.c > > > @@ -2542,6 +2542,46 @@ int machine__get_kernel_start(struct machine > > *machine) > > > return err; > > > }
> > > +/* > > > + * machine__single_ku_as - Machine has same address space for kernel > > and user. > > > + * @machine: machine object > > > + * > > > + * Some architectures have a single address space for kernel and user > > > +addresses, > > > + * which makes it possible to determine if an address is in kernel > > > +space or user > > > + * space. > > > + */ > > > +static bool machine__single_ku_as(struct machine *machine) { > > > + return strcmp(perf_env__arch(machine->env), "sparc"); }
> > Can we avoid having this strcmp be done repeatedly? > It is only done if there are mapping errors > > Can we avoid having this strcmp be done repeatedly? I.e. just make this a > > boolean initialized at session start, when machine->env is setup, so we'd > > have:
> > machine->single_address_space
> > Instead of a function? > Sure thing.
Thanks
> > > > Also have you considered making this fallback to be performed only from > > code that is that arch specific? > > > > I.e. the code that supports branch samples/stacks is x86_86 specific at this > > point and thus only in that case we would call the routines that perform the > > fallback, which, in turn, wouldn't need to check for "sparc"?
> I will look at it, but theoretically someone could be processing x86 data but > doing it on a machine of a different architecture.
Right, that should be supported, yes. What I meant was that when processing perf.data file with samples where the cpumode can't be inferred, we should use the fallback routines.
It is super unfortunate that we have addresses without a accompanying cpumode :-\ Don't you think those coulde be fixed somehow? If this comes from things synthesized from Intel PT traces, then we can use the address ranges for kernel/userspace to derive that before hitting the core code, that would be fed with addr/cpumode pairs, just like we have hdr.misc & USER/KERNEL and the PERF_CONTEXT_ markers in callchains.
- Arnaldo
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