On Fri, Sep 5, 2014 at 5:44 PM, Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote: > Em Sat, Sep 06, 2014 at 12:16:40AM +0900, Namhyung Kim escreveu: >> Hi Adrian and Arnaldo, >> >> 2014-09-05 (금), 11:11 -0300, Arnaldo Carvalho de Melo: >> > Em Fri, Sep 05, 2014 at 10:22:40AM +0300, Adrian Hunter escreveu: >> > > On 09/05/2014 07:59 AM, Namhyung Kim wrote: >> > > > +++ b/tools/perf/util/machine.c >> > > > @@ -1060,10 +1060,14 @@ static int machine__process_kernel_mmap_event(struct machine *machine, >> > > > strlen(kmmap_prefix)); >> > > > /* >> > > > * Should be there already, from the build-id table in >> > > > - * the header. >> > > > + * the header (but maybe with a different name: "vmlinux"). >> > > > */ >> > > > - struct dso *kernel = __dsos__findnew(&machine->kernel_dsos, >> > > > - kmmap_prefix); >> > > > + struct dso *kernel = dsos__find(&machine->kernel_dsos, >> > > > + "vmlinux", true); >> > >> > > Isn't "vmlinux" just the basename of the original file name, so if it had a >> > > different name this wouldn't work e.g. if the filename had been >> > > /boot/vmlinuz-3.11.0-26-generic then you would need >> > > "vmlinuz-3.11.0-26-generic" for this to work? >> > >> > Yeah, looking for well known pathnames to then check if the build-id >> > matches the one we're looking for, be it because we obtained it from >> > /sys/kernel/notes (for the running kernel), or from the perf.data file >> > build-id table is ok, as we don't know where it is. >> > >> > Plain sticking "vmlinux" there is not. >> >> I don't get it. AFAIK when perf record runs, it uses [kernel.kallsyms] >> name for kernel map. But it can be changed only if it found a "vmlinux" >> file in the vmlinux_path[]. So short name will always be "vmlinux" - >> okay, it might be vmlinux-$(uname -r) too; I can add it. >> >> As you know, the vmlinux file is a ELF image that created during kernel >> build process so I guess its name is fixed. It's different from the >> vmlinu"z" which resides in /boot directory. >> >> Am I missing something? > > [acme@zoo linux]$ perf report --help 2>&1 | grep vmlin > -k, --vmlinux=<file> > vmlinux pathname > [acme@zoo linux]$ > > Yes, it is using [kernel.kallsyms].ref_reloc_sym for the synthesized > KERNEL mmap event, but it stores the full path in the build-id table. > > It seems we need a way to state that an entry in the build-id table is > for the kernel, without looking at its file name. That or to put the > build-id into the synthesized kernel mmap event. Which is better, > because: > Can't you figure out it is from the kernel (in perf record) by remembering you got the buildid from /sys/kernel/notes? > That leads to another problem that needs to get solved eventually: We > need to have the build-id into PERF_RECORD_MMAP, because we're now using > just the mmap filename as the key, not the contents, and for long > running sessions, DSOs can get updated, etc. > > - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html