[Crash-utility] [PATCH v3 0/1] Filter ps output by scheduling policy

[Dave Anderson]

Hi Oleksandr,

I finally got around to doing a code review today, and ended up making a few
minor changes to your patch:
 
 (1) Instead of defaulting to NORMAL, invalid arguments generate a FATAL
     error.
 (2) I reworded the help page entry, and moved it up into the restricted 
     process section instead of down in the "alternatives" section.
 (3) I moved the offset_table[] and size_table[] task_struct_policy members
     to the end of the arrays to prevent any breakage of pre-compiled
     extension modules.
 (4) Display the task_struct_policy offset and size table values in the
     dump_offset_table() function for "help -o".
 (5) Replaced the strdup() call with STRDUPBUF(), calloc() with GETBUF(),
     and free() calls with FREEBUF() to avoid using them during runtime. 

But I need you to re-work your sched_policy_bit_from_str() function so that it
will accept a hexadecimal number, i.e, "ps -y 0x2".  Granted it's not explicitly
allowed in the help page, but a user may see the policy expressed as a hexadecimal
value by "task" or "struct", and it seems too picky to just disallow it.

I've attached an updated version of the patch with the changes above.

Thanks,
  Dave



----- Original Message -----
> While analyzing vmcores from customers sometimes we want
> to filter tasks by scheduling policy, for instance, to identify
> if customer runs realtime tasks. Doing this via foreach grepping
> and then feeding back pointers to task_struct and grepping it again
> is very slow, especially if customer runs thousands of tasks.
> 
> So, let's add another option for ps to filter tasks by scheduling
> policy.
> 
> Changes in v3:
> 
> * fix snprintf format specifier for ulong
> * fix snprintf block indentation
> * add one more comma to help output
> 
> Changes in v2:
> 
> * handle task_struct.policy member size correctly
> * accept comma-separated list of policies
>   instead of requiring multiple -y arguments
> * policy can be specified as a number too
> * policy name is case-insensitive now
> * warn about incorrect policy name
> * fix help message formatting
> * mark upper_case() source string pointer as a const
>   (minor cleanup)
> 
> Oleksandr Natalenko (1):
>   task: also filter ps output by ->policy
> 
>  defs.h  |  15 +++++++-
>  help.c  |   7 +++-
>  task.c  | 135
>  +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  tools.c |   5 ++-
>  4 files changed, 152 insertions(+), 10 deletions(-)
> 
> --
> 2.14.2
> 
> 
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