Messages in this thread | | | From | Arnaldo Carvalho de Melo <> | Date | Mon, 11 Nov 2019 11:06:25 -0300 | Subject | Re: [PATCH v2 1/4] perf probe: Generate event name with line number |
| |
Em Mon, Nov 11, 2019 at 11:04:50AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Fri, Nov 08, 2019 at 01:27:58AM +0900, Masami Hiramatsu escreveu: > > Generate event name from function name with line number > > as <function>_L<line_number>. Note that this is only for > > the new event which is defined by the line number of > > function (except for line 0). > > > > If there is another event on same line, you have to use > > "-f" option. In that case, the new event has "_1" suffix. > > > > e.g. > > # perf probe -a kernel_read:1 > > Added new events: > > probe:kernel_read_L1 (on kernel_read:1) > > While testing this, using the same function (kernel_read), I found it > confusing that it is possible to insert probes in lines seemingly with > no code, for instance: > > [root@quaco ~]# perf probe -a kernel_read:1 > Added new event: > probe:kernel_read_L1 (on kernel_read:1) > > You can now use it in all perf tools, such as: > > perf record -e probe:kernel_read_L1 -aR sleep 1 > > [root@quaco ~]# perf probe -a kernel_read:2 > Added new event: > probe:kernel_read_L2 (on kernel_read:2) > > You can now use it in all perf tools, such as: > > perf record -e probe:kernel_read_L2 -aR sleep 1 > > # > # perf probe --list > probe:kernel_read_l1 (on kernel_read@fs/read_write.c) > probe:kernel_read_l2 (on kernel_read:1@fs/read_write.c)
Also look above at the listing, I would expect this instead:
# perf probe --list probe:kernel_read_l1 (on kernel_read:1@fs/read_write.c) probe:kernel_read_l2 (on kernel_read:2@fs/read_write.c)
Right?
- Arnaldo
> [root@quaco ~]# perf probe -L kernel_read > <kernel_read@/usr/src/debug/kernel-5.3.fc30/linux-5.3.8-200.fc30.x86_64/fs/read_write.c:0> > 0 ssize_t kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) > 1 { > 2 mm_segment_t old_fs; > 3 ssize_t result; > > 5 old_fs = get_fs(); > 6 set_fs(KERNEL_DS); > /* The cast to a user pointer is valid due to the set_fs() */ > 8 result = vfs_read(file, (void __user *)buf, count, pos); > 9 set_fs(old_fs); > 10 return result; > } > EXPORT_SYMBOL(kernel_read); > > > [root@quaco ~]# > > > What is the point of putting a probe on line 2? I is not initializing, > etc, 1 as well, notthing there and we already have 0 (or not specifying > a line number) to put a probe at the start of a function, can you > clarify? > > I'll apply this patch, the problem above isn't strictly related to it. > > - Arnaldo
--
- Arnaldo
| |