linux-kernel - Re: [PATCH 4/5] mm/slub: sort debugfs output by frequency of stack traces

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Date:   Sat, 26 Feb 2022 11:03:05 +0000
From:   Hyeonggon Yoo <42.hyeyoo@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     David Rientjes <rientjes@...gle.com>,
        Christoph Lameter <cl@...ux.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Pekka Enberg <penberg@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        patches@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Oliver Glitta <glittao@...il.com>,
        Faiyaz Mohammed <faiyazm@...eaurora.org>
Subject: Re: [PATCH 4/5] mm/slub: sort debugfs output by frequency of stack
 traces

On Fri, Feb 25, 2022 at 07:03:17PM +0100, Vlastimil Babka wrote:
> From: Oliver Glitta <glittao@...il.com>
> 
> Sort the output of debugfs alloc_traces and free_traces by the frequency
> of allocation/freeing stack traces. Most frequently used stack traces
> will be printed first, e.g. for easier memory leak debugging.
> 
> Signed-off-by: Oliver Glitta <glittao@...il.com>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---
>  mm/slub.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 06599db4faa3..a74afe59a403 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -38,6 +38,7 @@
>  #include <linux/memcontrol.h>
>  #include <linux/random.h>
>  #include <kunit/test.h>
> +#include <linux/sort.h>
>  
>  #include <linux/debugfs.h>
>  #include <trace/events/kmem.h>
> @@ -6150,6 +6151,17 @@ static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos)
>  	return NULL;
>  }
>  
> +static int cmp_loc_by_count(const void *a, const void *b, const void *data)
> +{
> +	struct location *loc1 = (struct location *)a;
> +	struct location *loc2 = (struct location *)b;
> +
> +	if (loc1->count > loc2->count)
> +		return -1;
> +	else
> +		return 1;
> +}
> +
>  static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
>  {
>  	struct loc_track *t = seq->private;
> @@ -6211,6 +6223,10 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
>  		spin_unlock_irqrestore(&n->list_lock, flags);
>  	}
>  
> +	/* Sort locations by count */
> +	sort_r(t->loc, t->count, sizeof(struct location),
> +		cmp_loc_by_count, NULL, NULL);
> +
>  	bitmap_free(obj_map);
>  	return 0;
>  }

This is so cool!

Reviewed-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
Tested-by: Hyeonggon Yoo <42.hyeyoo@...il.com>

> -- 
> 2.35.1
> 
> 

-- 
Thank you, You are awesome!
Hyeonggon :-)