maxactive(NNNN) usage

maxactive(NNNN) usage

[Jey Jay]

All,

Greetings,

Below is a sample script(maxactive not included).
===================================

probe kernel.function("vfs_read").call {
            printf("hai: %d\t", bytes_read)
}
probe kernel.function("vfs_read").return {
            printf("Testing.... Jay")
}

$/bin/staprun  maxactive05.ko -c 'ls'

----- probe hit report:
kernel.function("vfs_read@fs/read_write.c:353").call,
(maxactive05.stp:6:1), hits: 18, cycles: 0min/0avg/0max, from:
kernel.function("vfs_read").call, index: 0
WARNING: Skipped due to missed kretprobe/1 on
'kernel.function("vfs_read@fs/read_write.c:353").return': 3
WARNING: Number of errors: 0, skipped probes: 3

Below is a sample script(maxactive included).
=================================

probe kernel.function("vfs_read").call {
            printf("hai: %d\t", bytes_read)
}
probe kernel.function("vfs_read").return.maxactive(1000) {
            printf("Testing.... Jay")
}

$/bin/staprun  maxactive05.ko -c 'ls'

Note: It prints hai: 0 16 times.

----- probe hit report:
kernel.function("vfs_read@fs/read_write.c:353").call,
(maxactive05.stp:6:1), hits: 18, cycles: 0min/0avg/0max, from:
kernel.function("vfs_read").call, index: 0

But there is no response for .return. i.e I'm expecting
printf("Testing.... Jay") statement to be executed. Any guidance will
help me lot..

Thanks in advance.

Regards
Jeyaram

Re: maxactive(NNNN) usage

[Frank Ch. Eigler]

Jey Jay <rjayavrp2@gmail.com> writes:

> [...]
> Below is a sample script(maxactive included).
> [...]
> ----- probe hit report:
> kernel.function("vfs_read@fs/read_write.c:353").call,
> (maxactive05.stp:6:1), hits: 18, cycles: 0min/0avg/0max, from:
> kernel.function("vfs_read").call, index: 0

> But there is no response for .return. i.e I'm expecting
> printf("Testing.... Jay") statement to be executed. Any guidance
> will help me lot..  Jeyaram

This is working here on various Fedora/RHEL platforms and on various
systemtap versions.  Perhaps the data generated by stap-report might
help point a finger at a kernel or systemtap version or configuration
problem.

- FChE

Re: maxactive(NNNN) usage

[Jey Jay]

Frank Ch. Eigler <fche@redhat.com> writes:

> This is working here on various Fedora/RHEL platforms and on various
> systemtap versions.  Perhaps the data generated by stap-report might
> help point a finger at a kernel or systemtap version or configuration
> problem.

There was a problem in kprobes. Now this works fine. thanks for the support.

- Jeyaram


On Tue, Jan 7, 2014 at 1:46 AM, Frank Ch. Eigler <fche@redhat.com> wrote:
> Jey Jay <rjayavrp2@gmail.com> writes:
>
>> [...]
>> Below is a sample script(maxactive included).
>> [...]
>> ----- probe hit report:
>> kernel.function("vfs_read@fs/read_write.c:353").call,
>> (maxactive05.stp:6:1), hits: 18, cycles: 0min/0avg/0max, from:
>> kernel.function("vfs_read").call, index: 0
>
>> But there is no response for .return. i.e I'm expecting
>> printf("Testing.... Jay") statement to be executed. Any guidance
>> will help me lot..  Jeyaram
>
> This is working here on various Fedora/RHEL platforms and on various
> systemtap versions.  Perhaps the data generated by stap-report might
> help point a finger at a kernel or systemtap version or configuration
> problem.
>
> - FChE