Messages in this thread | | | Date | Wed, 30 Apr 2014 09:35:55 -0400 | From | Don Zickus <> | Subject | Re: [PATCHSET 00/17] perf report: Add -F option for specifying output fields (v4) |
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On Wed, Apr 30, 2014 at 08:38:10AM +0900, Namhyung Kim wrote: > Hi Don, > > On Tue, 29 Apr 2014 13:27:35 -0400, Don Zickus wrote: > > On Tue, Apr 29, 2014 at 10:13:35AM +0900, Namhyung Kim wrote: > >> > /* > >> > * Addresses with no major/minor numbers are assumed to be > >> > * anonymous in userspace. Sort those on pid then address. > >> > * > >> > * The kernel and non-zero major/minor mapped areas are > >> > * assumed to be unity mapped. Sort those on address. > >> > */ > >> > > >> > if ((left->cpumode != PERF_RECORD_MISC_KERNEL) && > >> > !l_map->maj && !l_map->min && !l_map->ino && > >> > !l_map->ino_generation) { > >> > /* userspace anonymous */ > >> > > >> > if (left->thread->pid_ > right->thread->pid_) return -1; > >> > if (left->thread->pid_ < right->thread->pid_) return 1; > >> > >> Isn't it necessary to check whether the address is in a same map in case > >> of anon pages? I mean the daddr.al_addr is a map-relative offset so it > >> might have same value for different maps. > > > > That's why I sort on pids here. Because the anon address might have the > > same value for different maps. The thought was to group all the pid > > addresses together to keep things seperated. > > > > Do you see a different way to solve the problem? I am not sure al_addr > > vs. addr will make much difference here. > > I'm not saying to get rid of the pid check, I'm saying that it might > need to add another check for maps (i.e. start address) as there might > be many maps in a single address space.
Hmm, I guess I would need to see an example. While I agree there might be many maps in a single address space (/proc/<pid>/maps demonstrates that), I understood them to map to a unique location (ie no overlap) unless they are shared.
I am willing to believe I missed scenario when sorting, I just can't think of it (so I wouldn't know how to fix it). That's why I was looking for an example to make it more obvious to me. Sorry for being slow..
Cheers, Don
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