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

Hyeonggon Yoo
2022-05-31T11:47:07Z

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@openvz.org>
> Acked-by: Shakeel Butt <shakeelb@google.com>
> Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
>
> ---
> 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@gmail.com>

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);
> ),