Hi,
I am trying to find a way to make statistics for memory allocation of my device driver.
I want to know how much memory it allocates and how many times it calls kmalloc().
So I am considering to use kprobe but I think it doesn't provide a way to identify who makes the probe point.
Can I distinguish kmalloc() calling only from my driver?
For example I think it could be like this:
diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
index 1041b67..5322e0a 100644
--- a/samples/kprobes/kretprobe_example.c
+++ b/samples/kprobes/kretprobe_example.c
@@ -32,6 +32,7 @@ MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
/* per-instance private data */
struct my_data {
+ unsigned long signature;
ktime_t entry_stamp;
};
@@ -43,8 +44,10 @@ static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
if (!current->mm)
return 1; /* Skip kernel threads */
- data = (struct my_data *)ri->data;
- data->entry_stamp = ktime_get();
+ if (signature == 0xabcdabcd) {
+ data = (struct my_data *)ri->data;
+ data->entry_stamp = ktime_get();
+ }
return 0;
}
@@ -60,10 +63,12 @@ static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
s64 delta;
ktime_t now;
- now = ktime_get();
- delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
- printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
- func_name, retval, (long long)delta);
+ if (signature == 0xabcdabcd) {
+ now = ktime_get();
+ delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
+ printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
+ func_name, retval, (long long)delta);
+ }
return 0;
}
--
Thanks,
Gioh Kim
Hello Gioh,
If you can use ftrace and perftool, you can also put probes on
caller site. perf-probe will give you source-code level probes.
Or, just trace kmalloc event with ftrace stacktrace option, which
gives you caller information so that you can filter your driver
by postprocessing.
Thank you,
(2014/10/14 11:16), Gioh Kim wrote:
>
> Hi,
>
> I am trying to find a way to make statistics for memory allocation of my device driver.
> I want to know how much memory it allocates and how many times it calls kmalloc().
>
> So I am considering to use kprobe but I think it doesn't provide a way to identify who makes the probe point.
> Can I distinguish kmalloc() calling only from my driver?
>
> For example I think it could be like this:
>
> diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
> index 1041b67..5322e0a 100644
> --- a/samples/kprobes/kretprobe_example.c
> +++ b/samples/kprobes/kretprobe_example.c
> @@ -32,6 +32,7 @@ MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
>
> /* per-instance private data */
> struct my_data {
> + unsigned long signature;
> ktime_t entry_stamp;
> };
>
> @@ -43,8 +44,10 @@ static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
> if (!current->mm)
> return 1; /* Skip kernel threads */
>
> - data = (struct my_data *)ri->data;
> - data->entry_stamp = ktime_get();
> + if (signature == 0xabcdabcd) {
> + data = (struct my_data *)ri->data;
> + data->entry_stamp = ktime_get();
> + }
> return 0;
> }
>
> @@ -60,10 +63,12 @@ static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
> s64 delta;
> ktime_t now;
>
> - now = ktime_get();
> - delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
> - printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
> - func_name, retval, (long long)delta);
> + if (signature == 0xabcdabcd) {
> + now = ktime_get();
> + delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
> + printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
> + func_name, retval, (long long)delta);
> + }
> return 0;
> }
>
>
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: [email protected]
I'm going to try them.
Thanks a lot.
2014-10-16 ???? 3:00, Masami Hiramatsu ?? ??:
> Hello Gioh,
>
> If you can use ftrace and perftool, you can also put probes on
> caller site. perf-probe will give you source-code level probes.
> Or, just trace kmalloc event with ftrace stacktrace option, which
> gives you caller information so that you can filter your driver
> by postprocessing.
>
> Thank you,
>
> (2014/10/14 11:16), Gioh Kim wrote:
>>
>> Hi,
>>
>> I am trying to find a way to make statistics for memory allocation of my device driver.
>> I want to know how much memory it allocates and how many times it calls kmalloc().
>>
>> So I am considering to use kprobe but I think it doesn't provide a way to identify who makes the probe point.
>> Can I distinguish kmalloc() calling only from my driver?
>>
>> For example I think it could be like this:
>>
>> diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
>> index 1041b67..5322e0a 100644
>> --- a/samples/kprobes/kretprobe_example.c
>> +++ b/samples/kprobes/kretprobe_example.c
>> @@ -32,6 +32,7 @@ MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
>>
>> /* per-instance private data */
>> struct my_data {
>> + unsigned long signature;
>> ktime_t entry_stamp;
>> };
>>
>> @@ -43,8 +44,10 @@ static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
>> if (!current->mm)
>> return 1; /* Skip kernel threads */
>>
>> - data = (struct my_data *)ri->data;
>> - data->entry_stamp = ktime_get();
>> + if (signature == 0xabcdabcd) {
>> + data = (struct my_data *)ri->data;
>> + data->entry_stamp = ktime_get();
>> + }
>> return 0;
>> }
>>
>> @@ -60,10 +63,12 @@ static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
>> s64 delta;
>> ktime_t now;
>>
>> - now = ktime_get();
>> - delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
>> - printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
>> - func_name, retval, (long long)delta);
>> + if (signature == 0xabcdabcd) {
>> + now = ktime_get();
>> + delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
>> + printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
>> + func_name, retval, (long long)delta);
>> + }
>> return 0;
>> }
>>
>>
>
>