> > // always fails, with errno = 2 > procmap = fopen(procmap_filename, "r"); >
errno 2 (ENOENT) means file does not exist. You can add additional print to check whether the file truly exists or not. On Sat, Aug 12, 2017 at 5:14 AM, Fenggang Wu via iovisor-dev <iovisor-dev@lists.iovisor.org> wrote: > Hi there, > > I am trying out bcc tools from http://github.com/iovisor/bcc, more > specificaly profile.py and offcputime.py. However in the tracing result, > user functions are shown as "[unknown]", whereas kernel functions such as > "sys_*" are interpreted well. Any ideas? > > Thank you very much! > Fenggang > > ====== > > Here are more details (I use profile.py as the example). If there are more > details that are necessary please feel free to let me know. > > 1) how to reproduce the issue: > #~> cat Makefile > all: > g++ -o spin spin.cc > objcopy --only-keep-debug spin spin.debug > objcopy --add-gnu-debuglink=spin.debug spin > > > clean: > rm spin spin.debug > #~> cat spin.cc > #include<iostream> > using namespace std; > void myfunc() { > int i, j, cnt; > cout << "my func" << endl; > for (i = 0; i < 4; i++) { > for ( j = 0; j < 500000000; j++) { > cnt ^= i + j; > } > cout << i << " " << cnt; > } > } > > int main() { > cout << "hello" << endl; > myfunc(); > } > #~> cat test_profile.sh > #!/bin/bash > sudo make > > sudo -- bash -c "./spin & PID=\$!; echo PID=\$PID; cat /proc/\$PID/maps; > (trap - SIGINT; profile -U -p \$PID > spin.profile)& wait \$PID;"; sudo kill > -SIGINT `pgrep -x profile`; sleep 1; cat spin.profile; > sleep 1 > sudo make clean > > #~>./test_profile.sh > > Here, in my server, spin.profile cannot resolve user-level symbols (i.e. > symbols in spin.cc). It only shows userland symbol names as "[unknown]". > > I am using Ubuntu 16.04.3 LTS with Linux Kernel ver. 4.10.0-28-generic. I've > tried both installing by apt-get or building from source (latest pull from > github). the results are the same: user-land functions names cannot be > resolved. > > 2) What I've tried/found: > > - perf_event works well under my environment in resolving both the kernel > and userspace symbols. > - bcc/test/python/test_debuginfo.py pass all tests. Showing that build-id > and debug-link both methods work in bcc. > - [MAJOR PROBLEM] I found the failed statement: > src/cc/bcc_proc.c:78: > int bcc_procutils_each_module(int pid, bcc_procutils_modulecb callback, void > *payload) { > > ... > // always fails, with errno = 2 > procmap = fopen(procmap_filename, "r"); > ... > > } > > - Afterwards, I've written a similar little c++ program to read > "/proc/pid/maps", and it can open/read the proc map file successfully. > Besides, I can also cat the proc map file in the shell, the file can be read > successfully too. > > the little testing c++ program to open and read the procmap file is as > follows (very similar to bcc_procutils_each_module): > > #~> cat read-proc-map.cc > #include <iostream> > #include <cstring> > #include <stdio.h> > #include <errno.h> > > int main(int argc, char*argv[]) { > char procmap_filename[128]; > FILE *procmap; > int ret; > > printf("%d\n", argc); > > if (argc != 2) return -1; > > printf("mytest\n"); > > snprintf(procmap_filename, sizeof(procmap_filename), > "/proc/%s/maps", argv[1]); > procmap = fopen(procmap_filename, "r"); > > printf("mytest: fopen <%s>\n", procmap_filename); > > if (!procmap) { > printf("mytest: ... failed errno=%d\n", errno); > return -1; > } > > printf("mytest: ... success <%s>\n", procmap_filename); > > > do { > char endline[4096]; > char perm[8], dev[8]; > long long begin, end, size, inode; > > ret = fscanf(procmap, "%llx-%llx %s %llx %s %lld", &begin, &end, perm, > &size, dev, &inode); > > if (!fgets(endline, sizeof(endline), procmap)) > break; > > if (ret == 6) { > char *mapname = endline; > char *newline = strchr(endline, '\n'); > > if (newline) > newline[0] = '\0'; > > while (isspace(mapname[0])) mapname++; > > printf("%s, %llx, %llx\n", mapname, begin, end); > } > } while (ret && ret != EOF); > > fclose(procmap); > printf("mytest: fclosed %s\n", procmap_filename); > return 0; > } > > ==== > > _______________________________________________ > iovisor-dev mailing list > iovisor-dev@lists.iovisor.org > https://lists.iovisor.org/mailman/listinfo/iovisor-dev > _______________________________________________ iovisor-dev mailing list iovisor-dev@lists.iovisor.org https://lists.iovisor.org/mailman/listinfo/iovisor-dev
