[Crash-utility] [PATCH] speed up "ps -r" by storing the length of rlim array

[Dave Anderson]

----- Original Message -----
> Without this patch, the "ps -r" command takes one minute or more per 1,000
> tasks.  The cause is that getting the length of {task,signal}_struct.rlim
> array takes some time and it is done for each task.
> 
> This patch stores the value, and it will take only about 0.5 seconds per
> 1,000 tasks.
> 
> Signed-off-by: Kazuhito Hagio <k-hagio ab jp nec com>

Nice -- this is a huge performance improvement!  Queued for crash-7.2.2:

  https://github.com/crash-utility/crash/commit/6588de928a111dd10f74af2a624345d3ef6f98f2

Thanks,
  Dave


> --->  defs.h    | 2 ++
>  symbols.c | 8 ++++++++
>  task.c    | 6 ++++--
>  3 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/defs.h b/defs.h
> index adddb9f..4b6ebc2 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2191,6 +2191,8 @@ struct array_table {
>  	int kmem_cache_cpu_slab;
>  	int rt_prio_array_queue;
>  	int height_to_maxnodes;
> +	int task_struct_rlim;
> +	int signal_struct_rlim;
>  };
>  
>  /*
> diff --git a/symbols.c b/symbols.c
> index 638800a..e934e7f 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -8440,6 +8440,10 @@ builtin_array_length(char *s, int len, int *two_dim)
>  		lenptr = &array_table.kmem_cache_cpu_slab;
>  	else if (STREQ(s, "rt_prio_array.queue"))
>  		lenptr = &array_table.rt_prio_array_queue;
> +	else if (STREQ(s, "task_struct.rlim"))
> +		lenptr = &array_table.task_struct_rlim;
> +	else if (STREQ(s, "signal_struct.rlim"))
> +		lenptr = &array_table.signal_struct_rlim;
>  
>  	if (!lenptr)                /* not stored */
>  		return(len);        
> @@ -10520,6 +10524,10 @@ dump_offset_table(char *spec, ulong makestruct)
>  		ARRAY_LENGTH(kmem_cache_cpu_slab));
>          fprintf(fp, "           rt_prio_array_queue: %d\n",
>                  ARRAY_LENGTH(rt_prio_array_queue));
> +	fprintf(fp, "              task_struct_rlim: %d\n",
> +		ARRAY_LENGTH(task_struct_rlim));
> +	fprintf(fp, "            signal_struct_rlim: %d\n",
> +		ARRAY_LENGTH(signal_struct_rlim));
>  
>  	if (spec) {
>  		int in_size_table, in_array_table, arrays, offsets, sizes;
> diff --git a/task.c b/task.c
> index 560adfa..2418e4c 100644
> --- a/task.c
> +++ b/task.c
> @@ -4027,12 +4027,14 @@ show_task_rlimit(struct task_context *tc)
>  	in_task_struct = in_signal_struct = FALSE;
>  
>  	if (VALID_MEMBER(task_struct_rlim)) {
> -		rlimit_index = get_array_length("task_struct.rlim", NULL, 0);
> +		rlimit_index = (i = ARRAY_LENGTH(task_struct_rlim)) ?
> +			i : get_array_length("task_struct.rlim", NULL, 0);
>  		in_task_struct = TRUE;
>  	} else if (VALID_MEMBER(signal_struct_rlim)) {
>  		if (!VALID_MEMBER(task_struct_signal))
>  			error(FATAL, "cannot determine rlimit array location\n");
> -		rlimit_index = get_array_length("signal_struct.rlim", NULL, 0);
> +		rlimit_index = (i = ARRAY_LENGTH(signal_struct_rlim)) ?
> +			i : get_array_length("signal_struct.rlim", NULL, 0);
>  		in_signal_struct = TRUE;
>  	}
>  
> -- 
> 1.8.3.1
>