Re: [PATCH] S/390: Add event interface to the System z hardware sampling module

[Robert R. <rob...@am...>]

On 25.11.11 20:03:05, Andreas Krebbel wrote:
> With this patch the OProfile Basic Mode Sampling support for System z
> is enhanced with a counter file system.  That way hardware sampling
> can be configured using the user space tools with only little
> modifications.
> 
> With the patch by default new cpu_types (s390/z10, s390/z196) are
> returned in order to indicate that we are running a CPU which provides
> the hardware sampling facility.  Existing user space tools will
> complain about an unknown cpu type. In order to be compatible with
> existing user space tools the `cpu_type' module parameter has been
> added.  Setting the parameter to `timer' will force the module to
> return `timer' as cpu_type.  The module will still try to use hardware
> sampling if available and the hwsampling virtual filesystem will be
> also be available for configuration.  So this has a different effect
> than using the generic oprofile module parameter `timer=1'.
> 
> If the basic mode sampling is enabled on the machine and the
> cpu_type=timer parameter is not used the kernel module will provide
> the following virtual filesystem:
> 
> /dev/oprofile/0/enabled
> /dev/oprofile/0/event
> /dev/oprofile/0/count
> /dev/oprofile/0/unit_mask
> /dev/oprofile/0/kernel
> /dev/oprofile/0/user
> 
> In the counter file system only the values of 'enabled', 'count',
> 'kernel', and 'user' are evaluated by the kernel module. Everything
> else must contain fixed values.
> 
> The 'event' value only supports a single event - HWSAMPLING with value
> 0.
> 
> The 'count' value specifies the hardware sampling rate as it is passed
> to the CPU measurement facility.
> 
> The 'kernel' and 'user' flags can now be used to filter for samples
> when using hardware sampling.
> 
> Additionally also the following file will be created:
> /dev/oprofile/timer/enabled
> 
> This will always be the inverted value of /dev/oprofile/0/enabled. 0
> is not accepted without hardware sampling.
> 
> Signed-off-by: Andreas Krebbel <kr...@li...>
> ---
>  Documentation/kernel-parameters.txt |    2 
>  arch/s390/oprofile/hwsampler.c      |    7 
>  arch/s390/oprofile/init.c           |  373 +++++++++++++++++++++++++++++++++---
>  arch/s390/oprofile/op_counter.h     |   23 ++
>  4 files changed, 374 insertions(+), 31 deletions(-)

Applied to oprofile/core. Thanks Andreas.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center