Re: [PATCH v5] tracing: add 'accounted' entry into output of allocation tracepoints

[Hyeonggon Yoo]

On Mon, May 30, 2022 at 10:47:26AM +0300, Vasily Averin wrote:
> Slab caches marked with SLAB_ACCOUNT force accounting for every
> allocation from this cache even if __GFP_ACCOUNT flag is not passed.
> Unfortunately, at the moment this flag is not visible in ftrace output,
> and this makes it difficult to analyze the accounted allocations.
> 
> This patch adds boolean "accounted" entry into trace output,
> and set it to 'true' for calls used __GFP_ACCOUNT flag and
> for allocations from caches marked with SLAB_ACCOUNT.
> 
> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxx>
> Acked-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
> Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> 
> ---
> v5:
>  1) re-based to current upstream (v5.18-11267-gb00ed48bb0a7)
>  2) added "Acked-by" from Roman
>  3) re-addressed to slab maintaiers
> 
> v4:
>  1) replaced in patch descripion: "accounted" instead of "allocated"
>  2) added "Acked-by" from Shakeel,
>  3) re-addressed to akpm@
> 
> v3:
>  1) rework kmem_cache_alloc* tracepoints once again,
>     added struct kmem_cache argument into existing templates,
> 	thanks to Matthew Wilcox
>  2) updated according trace_* calls
>  3) added boolean "allocated" entry into trace output,
> 	thanks to Roman
>  4) updated patch subject and description
> 
> v2:
>  1) handle kmem_cache_alloc_node(), thanks to Shakeel
>  2) rework kmem_cache_alloc* tracepoints to use cachep instead
>     of current cachep->*size parameters.
>     NB: kmem_cache_alloc_node tracepoint in SLOB cannot use cachep,
>         and therefore it was replaced by kmalloc_node.
> ---
>  include/trace/events/kmem.h | 38 +++++++++++++++++++++++--------------
>  mm/slab.c                   | 10 +++++-----
>  mm/slab_common.c            |  9 ++++-----
>  mm/slob.c                   |  8 ++++----
>  mm/slub.c                   | 20 +++++++++----------
>  5 files changed, 47 insertions(+), 38 deletions(-)
> 

Looks good to me.
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>

a small comment:
>  
>  	TP_fast_assign(
> @@ -33,42 +35,46 @@ DECLARE_EVENT_CLASS(kmem_alloc,
>  		__entry->bytes_req	= bytes_req;
>  		__entry->bytes_alloc	= bytes_alloc;
>  		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
> +		__entry->accounted	= (gfp_flags & __GFP_ACCOUNT) ||
> +					  (s && s->flags & SLAB_ACCOUNT);
>  	),
>  

It doesn't make sense for SLOB to print accounted=true because SLOB does
not support object accounting.

>  DEFINE_EVENT(kmem_alloc, kmalloc,
>  
> -	TP_PROTO(unsigned long call_site, const void *ptr,
> +	TP_PROTO(unsigned long call_site, const void *ptr, struct kmem_cache *s,
>  		 size_t bytes_req, size_t bytes_alloc, gfp_t gfp_flags),
>  
> -	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags)
> +	TP_ARGS(call_site, ptr, s, bytes_req, bytes_alloc, gfp_flags)
>  );
>  
>  DEFINE_EVENT(kmem_alloc, kmem_cache_alloc,
>  
> -	TP_PROTO(unsigned long call_site, const void *ptr,
> +	TP_PROTO(unsigned long call_site, const void *ptr, struct kmem_cache *s,
>  		 size_t bytes_req, size_t bytes_alloc, gfp_t gfp_flags),
>  
> -	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags)
> +	TP_ARGS(call_site, ptr, s, bytes_req, bytes_alloc, gfp_flags)
>  );
>  
>  DECLARE_EVENT_CLASS(kmem_alloc_node,
>  
>  	TP_PROTO(unsigned long call_site,
>  		 const void *ptr,
> +		 struct kmem_cache *s,
>  		 size_t bytes_req,
>  		 size_t bytes_alloc,
>  		 gfp_t gfp_flags,
>  		 int node),
>  
> -	TP_ARGS(call_site, ptr, bytes_req, bytes_alloc, gfp_flags, node),
> +	TP_ARGS(call_site, ptr, s, bytes_req, bytes_alloc, gfp_flags, node),
>  
>  	TP_STRUCT__entry(
>  		__field(	unsigned long,	call_site	)
> @@ -77,6 +83,7 @@ DECLARE_EVENT_CLASS(kmem_alloc_node,
>  		__field(	size_t,		bytes_alloc	)
>  		__field(	unsigned long,	gfp_flags	)
>  		__field(	int,		node		)
> +		__field(	bool,		accounted	)
>  	),
>  
>  	TP_fast_assign(
> @@ -86,33 +93,36 @@ DECLARE_EVENT_CLASS(kmem_alloc_node,
>  		__entry->bytes_alloc	= bytes_alloc;
>  		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
>  		__entry->node		= node;
> +		__entry->accounted	= (gfp_flags & __GFP_ACCOUNT) ||
> +					  (s && s->flags & SLAB_ACCOUNT);
>  	),