Messages in this thread | | | Date | Thu, 3 Oct 2013 14:21:41 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [QUERY] Why does perf-trace need me to be root? |
| |
Em Thu, Oct 03, 2013 at 08:25:05AM +0200, Ingo Molnar escreveu: > * Ramkumar Ramachandra <artagnon@gmail.com> wrote: > > David Ahern wrote: > > > If you trust your users make the debugfs mount point rx by group,world.
> > Thanks David. I can preserve this configuration across reboots by > > putting an entry in fstab, right? How do I preserve the value of > > /proc/sys/kernel/perf_event_paranoid across reboots?
> via:
> echo 'kernel.perf_event_paranoid = -1' >> /etc/sysctl.conf
You don't need that, only if you want users to trace syswide or threads from other users:
[acme@zoo linux]$ cat /proc/sys/kernel/perf_event_paranoid 1 [acme@zoo linux]$ trace -e brk usleep 1 0.420 ( 0.001 ms): brk( ) = 0x2427000 0.698 ( 0.002 ms): brk( ) = 0x2427000 0.702 ( 0.002 ms): brk(brk: 0x2448000 ) = 0x2448000 0.704 ( 0.001 ms): brk( ) = 0x2448000 [acme@zoo linux]$
When doing syswide we get another message that can get some love and care:
[acme@zoo linux]$ trace -a Couldn't create the events: Operation not permitted
Here we should tell that if this is done, as you suggested above:
[root@zoo ~]# echo -1 > /proc/sys/kernel/perf_event_paranoid
Then lets do syswide tracing filtering out common syscalls:
[acme@zoo linux]$ trace -a -e \!write,lseek,ioctl,recvfrom,read,open,getrlimit,writev,poll,rt_sigprocmask,brk,,timer_gettime,timer_settime,gettid,setitimer,select,rt_sigaction,nanosleep,newfstatat,stat,close,openat,getdents,recvmsg,epoll_wait,sendmsg,futex,mmap,munmap,getsockopt,getegid,geteuid,lstat,fstat,inotify_add_watch,exit,madvise,fcntl,alarm,exit_group,wait4,unlink,link,dup,sendto,getuid,setgid,uname,umask,getgid,fsync,chdir,setuid,setreuid,setregid,socket,connect,access,mprotect,getpgrp,setresgid,getpid,execve,dup2,clone,getsockname,bind,arch_prctl,statfs,getppid,pipe2,capget,readlink,fstatfs 90.964 ( 0.001 ms): python/7597 set_robust_list(head: 0x7ff5cf2d09e0, len: 24 ) = 0 1092.945 ( 0.002 ms): python/7598 set_robust_list(head: 0x7ff5cf2d09e0, len: 24 ) = 0 1104.372 ( 0.004 ms): fetchmail/2333 setresuid(ruid: -1, euid: 1000, suid: -1 ) = 0 1104.589 ( 0.003 ms): fetchmail/2333 setresuid(ruid: -1, euid: 1000, suid: -1 ) = 0 1104.869 ( 0.002 ms): fetchmail/7599 set_robust_list(head: 0x7f4d97395ae0, len: 24 ) = 0 2095.270 ( 0.001 ms): python/7600 set_robust_list(head: 0x7ff5cf2d09e0, len: 24 ) = 0 2581.513 ( 0.004 ms): fetchmail/2333 setresuid(ruid: -1, euid: 1000, suid: -1 ) = 0 2581.676 ( 0.002 ms): fetchmail/7601 set_robust_list(head: 0x7f4d97395ae0, len: 24 ) = 0 2581.688 ( 0.003 ms): fetchmail/2333 setresuid(ruid: -1, euid: 1000, suid: -1 ) = 0 3097.509 ( 0.002 ms): python/7602 set_robust_list(head: 0x7ff5cf2d09e0, len: 24 ) = 0 4100.418 ( 0.001 ms): python/7603 set_robust_list(head: 0x7ff5cf2d09e0, len: 24 ) = 0 ^C[acme@zoo linux]$
> I think 'perf trace' should probably print such suggestions when it > notices a privilege problem, to make it far more obvious for new users to > correctly configure their system for easy tracing. > > The current output: > > comet:~/tip> perf trace > Couldn't read the raw_syscalls tracepoints information! > > is as hostile to the user as it gets ;-)
Yes, its good that there are users now! ;-)
- Arnaldo
| |