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RE: [PATCH RFC V2 00/10] perf top optimization

From "Liang, Kan" <kan.liang@intel.com>
Newsgroups linux.kernel
Subject RE: [PATCH RFC V2 00/10] perf top optimization
Date 2017-09-15 17:20 +0200
Message-ID <uq0zo-4II-15@gated-at.bofh.it> (permalink)
References <uomE1-4Gu-1@gated-at.bofh.it> <uphLY-DH-19@gated-at.bofh.it> <uphLY-DH-17@gated-at.bofh.it> <uphVD-H9-7@gated-at.bofh.it> <upJId-1Oa-1@gated-at.bofh.it>
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> Em Wed, Sep 13, 2017 at 12:38:19PM -0300, Arnaldo Carvalho de Melo
> escreveu:
> > Em Wed, Sep 13, 2017 at 03:29:44PM +0000, Liang, Kan escreveu:
> > > >
> > > > Em Sun, Sep 10, 2017 at 07:23:13PM -0700, kan.liang@intel.com
> escreveu:
> > > >
> > > > So I got the first two patches already merged, and made some
> > > > comments about the other patches, please check those,
> > > >
> > >
> > > Thanks for the review Arnaldo.
> > >
> > > I will take a close look for the comments.
> > > For the next version, I only need to include patch 3-10, correct?
> >
> > Right, and go from my perf/core branch. The hashtable patch is still
> > not there as I am running tests before pushing out, but it should be
> > there later today.
> 
> So, its at my repo, branch tmp.perf/threads_hashtable
> 
> But 'perf trace' is broken, please take a look below:
> 
> [root@jouet ~]# gdb -c core
> GNU gdb (GDB) Fedora 8.0-20.fc26
> <SNIP>
> Core was generated by `perf trace -e block:block_bio_queue'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0  0x000000000051089a in ?? ()
> (gdb) file perf
> Reading symbols from perf...done.
> (gdb) bt
> #0  0x000000000051089a in ____machine__findnew_thread
> (machine=0x3dfcab0, threads=0x3dfca78, pid=-1, tid=-1, create=false) at
> util/machine.c:429

I think the root cause is tid==-1. So the index of hashtable will be -1.
The patch as below should fix it.

diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index e6d5381..3c564b8 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -57,7 +57,7 @@ struct machine {
 
 static inline struct threads *machine__threads(struct machine *machine, pid_t tid)
 {
-	return &machine->threads[tid % THREADS__TABLE_SIZE];
+	return &machine->threads[(unsigned int)tid % THREADS__TABLE_SIZE];
 }
 
 static inline


There should be another issue which was introduced by  
33013b9a5607 ("perf machine: Optimize a bit the machine__findnew_thread() methods")
It should use tid not pid to get the threads.

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 90ae9c7..ddeea05 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -473,7 +473,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine,
 
 struct thread *__machine__findnew_thread(struct machine *machine, pid_t pid, pid_t tid)
 {
-	return ____machine__findnew_thread(machine, machine__threads(machine, pid), pid, tid, true);
+	return ____machine__findnew_thread(machine, machine__threads(machine, tid), pid, tid, true);
 }

They are small fixes. I think it's better to merge them with the old patches.
Should I include the modified hashtable patches in V3?

Thanks,
Kan

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[PATCH RFC V2 00/10] perf top optimization kan.liang@intel.com - 2017-09-11 04:30 +0200
  [PATCH RFC V2 10/10] perf top: switch back to overwrite mode kan.liang@intel.com - 2017-09-11 04:30 +0200
  [PATCH RFC V2 04/10] petf tools: introduce a new function to set namespaces id kan.liang@intel.com - 2017-09-11 04:30 +0200
  [PATCH RFC V2 06/10] perf tools: lock to protect comm_str rb tree kan.liang@intel.com - 2017-09-11 04:30 +0200
  [PATCH RFC V2 02/10] perf tools: using scandir to replace readdir kan.liang@intel.com - 2017-09-11 04:30 +0200
    Re: [PATCH RFC V2 02/10] perf tools: using scandir to replace readdir Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-13 17:30 +0200
  [PATCH RFC V2 03/10] petf tools: using comm_str to replace comm in hist_entry kan.liang@intel.com - 2017-09-11 04:30 +0200
    Re: [PATCH RFC V2 03/10] petf tools: using comm_str to replace comm  in hist_entry Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-13 17:30 +0200
      Re: [PATCH RFC V2 03/10] petf tools: using comm_str to replace comm  in hist_entry Jiri Olsa <jolsa@redhat.com> - 2017-09-18 10:40 +0200
  [PATCH RFC V2 01/10] perf tools: hashtable for machine threads kan.liang@intel.com - 2017-09-11 04:30 +0200
    Re: [PATCH RFC V2 01/10] perf tools: hashtable for machine threads Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-13 15:30 +0200
    [tip:perf/core] perf machine: Use hashtable for machine threads tip-bot for Kan Liang <tipbot@zytor.com> - 2017-09-22 18:50 +0200
  [PATCH RFC V2 08/10] perf top: implement multithreading for perf_event__synthesize_threads kan.liang@intel.com - 2017-09-11 04:30 +0200
    Re: [PATCH RFC V2 08/10] perf top: implement multithreading for  perf_event__synthesize_threads Jiri Olsa <jolsa@redhat.com> - 2017-09-18 13:30 +0200
  [PATCH RFC V2 07/10] perf tools: change machine comm_exec type to atomic kan.liang@intel.com - 2017-09-11 04:30 +0200
    Re: [PATCH RFC V2 07/10] perf tools: change machine comm_exec type  to atomic Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-13 17:30 +0200
      RE: [PATCH RFC V2 07/10] perf tools: change machine comm_exec type  to atomic "Liang, Kan" <kan.liang@intel.com> - 2017-09-15 22:10 +0200
        Re: [PATCH RFC V2 07/10] perf tools: change machine comm_exec type  to atomic Jiri Olsa <jolsa@redhat.com> - 2017-09-18 13:40 +0200
  [PATCH RFC V2 05/10] perf tools: lock to protect thread list kan.liang@intel.com - 2017-09-11 04:30 +0200
    Re: [PATCH RFC V2 05/10] perf tools: lock to protect thread list Jiri Olsa <jolsa@redhat.com> - 2017-09-18 11:00 +0200
      RE: [PATCH RFC V2 05/10] perf tools: lock to protect thread list "Liang, Kan" <kan.liang@intel.com> - 2017-09-18 18:20 +0200
  [PATCH RFC V2 09/10] perf top: add option to set the number of thread for event synthesize kan.liang@intel.com - 2017-09-11 04:30 +0200
  RE: [PATCH RFC V2 00/10] perf top optimization "Liang, Kan" <kan.liang@intel.com> - 2017-09-13 17:30 +0200
    Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-13 17:40 +0200
      Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-14 23:20 +0200
        RE: [PATCH RFC V2 00/10] perf top optimization "Liang, Kan" <kan.liang@intel.com> - 2017-09-15 17:20 +0200
          Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-15 19:30 +0200
            RE: [PATCH RFC V2 00/10] perf top optimization "Liang, Kan" <kan.liang@intel.com> - 2017-09-15 19:30 +0200
              Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-15 20:30 +0200
                RE: [PATCH RFC V2 00/10] perf top optimization "Liang, Kan" <kan.liang@intel.com> - 2017-09-15 20:30 +0200
  Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-13 17:30 +0200
  Re: [PATCH RFC V2 00/10] perf top optimization Jiri Olsa <jolsa@redhat.com> - 2017-09-18 11:00 +0200
    Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-18 15:10 +0200
      RE: [PATCH RFC V2 00/10] perf top optimization "Liang, Kan" <kan.liang@intel.com> - 2017-09-18 18:30 +0200
      Re: [PATCH RFC V2 00/10] perf top optimization Jiri Olsa <jolsa@redhat.com> - 2017-09-19 10:20 +0200
        RE: [PATCH RFC V2 00/10] perf top optimization "Liang, Kan" <kan.liang@intel.com> - 2017-09-19 14:50 +0200
          Re: [PATCH RFC V2 00/10] perf top optimization Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-09-19 16:30 +0200

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