Messages in this thread | | | Date | Fri, 15 May 2009 09:33:27 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2] perf_counter: Allow specifying a pid to record |
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* Arnaldo Carvalho de Melo <acme@redhat.com> wrote:
> Em Thu, May 14, 2009 at 10:45:27PM -0300, Arnaldo Carvalho de Melo escreveu: > > commit ee8ffeaf1ba6aee56cf822cba291fbacb5dd450b > > Author: Arnaldo Carvalho de Melo <acme@redhat.com> > > Date: Thu May 14 22:41:18 2009 -0300 > > > > perf_count: Allow connecting to an existing thread > > > > Impact: new command line option > > > > Allow specifying a pid instead of always fork+exec'ing a command. > > > > Because the PERF_EVENT_COMM and PERF_EVENT_MMAP events happened before > > we connected, we must synthesize them so that 'perf record' can get what > > it needs. > > Grr, it should read "so that 'perf report' can get", new patch below. > > commit 37216038fe2807ee0725e221675914cd41233541 > Author: Arnaldo Carvalho de Melo <acme@redhat.com> > Date: Thu May 14 22:41:18 2009 -0300 > > perf_count: Allow connecting to an existing thread > > Impact: new command line option > > Allow specifying a pid instead of always fork+exec'ing a command. > > Because the PERF_EVENT_COMM and PERF_EVENT_MMAP events happened before > we connected, we must synthesize them so that 'perf report' can get what > it needs. > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Very nice, applied it - thanks Arnaldo!
> +static void pid_synthesize_mmap_events(pid_t pid, pid_t pgid) > +{ > + char filename[PATH_MAX]; > + FILE *fp; > + > + snprintf(filename, sizeof(filename), "/proc/%d/maps", pid); > + > + fp = fopen(filename, "r"); > + if (fp == NULL) { > + fprintf(stderr, "couldn't open %s\n", filename); > + exit(EXIT_FAILURE); > + } > + while (1) { > + char bf[BUFSIZ]; > + unsigned char vm_read, vm_write, vm_exec, vm_mayshare; > + struct mmap_event mmap_ev = { > + .header.type = PERF_EVENT_MMAP, > + }; > + unsigned long ino; > + int major, minor; > + size_t size; > + if (fgets(bf, sizeof(bf), fp) == NULL) > + break; > + > + /* 00400000-0040c000 r-xp 00000000 fd:01 41038 /bin/cat */ > + sscanf(bf, "%llx-%llx %c%c%c%c %llx %x:%x %lu", > + &mmap_ev.start, &mmap_ev.len, > + &vm_read, &vm_write, &vm_exec, &vm_mayshare, > + &mmap_ev.pgoff, &major, &minor, &ino); > + if (vm_exec == 'x') { > + char *execname = strrchr(bf, ' '); > + > + if (execname == NULL || execname[1] != '/') > + continue; > + > + execname += 1; > + size = strlen(execname); > + execname[size - 1] = '\0'; /* Remove \n */ > + memcpy(mmap_ev.filename, execname, size); > + size = ALIGN(size, sizeof(uint64_t)); > + mmap_ev.len -= mmap_ev.start; > + mmap_ev.header.size = (sizeof(mmap_ev) - > + (sizeof(mmap_ev.filename) - size)); > + mmap_ev.pid = pgid; > + mmap_ev.tid = pid; > + > + if (write(output, &mmap_ev, mmap_ev.header.size) < 0) { > + perror("failed to write"); > + exit(-1); > + } > + } > + } > + > + fclose(fp); > +}
Neat - this was one of the holes in the concept :)
Ingo
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