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Date:   Tue, 10 May 2022 19:33:17 -0700
From:   Roman Gushchin <roman.gushchin@linux.dev>
To:     Vasily Averin <vvs@openvz.org>
Cc:     Shakeel Butt <shakeelb@google.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, kernel@openvz.org,
        linux-kernel@vger.kernel.org, Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>, cgroups@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
        Christoph Lameter <cl@linux.com>, linux-mm@kvack.org
Subject: Re: [PATCH v2] percpu: improve percpu_alloc_percpu event trace
Message-ID: <YnsgbXKiNNSF+1ZO@carbon>
References: <2b388d09-940e-990f-1f8a-2fdaa9210fa0@openvz.org>
 <a07be858-c8a3-7851-9086-e3262cbcf707@openvz.org>
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On Fri, May 06, 2022 at 10:29:25PM +0300, Vasily Averin wrote:
> Added call_site, bytes_alloc and gfp_flags fields to the output
> of the percpu_alloc_percpu ftrace event:
> 
> mkdir-4393  [001]   169.334788: percpu_alloc_percpu:
>  call_site=mem_cgroup_css_alloc+0xa6 reserved=0 is_atomic=0 size=2408 align=8
>   base_addr=0xffffc7117fc00000 off=402176 ptr=0x3dc867a62300 bytes_alloc=14448
>    gfp_flags=GFP_KERNEL_ACCOUNT
> 
> This is required to track memcg-accounted percpu allocations.
> 
> Signed-off-by: Vasily Averin <vvs@openvz.org>

Acked-by: Roman Gushchin <roman.gushchin@linux.dev>

LGTM, thanks Vasily!

One minor thing below.

> ---
> v2: added call_site, improved patch description
> ---
>  include/trace/events/percpu.h | 23 +++++++++++++++++------
>  mm/percpu-internal.h          |  8 ++++----
>  mm/percpu.c                   |  5 +++--
>  3 files changed, 24 insertions(+), 12 deletions(-)
> 
> diff --git a/include/trace/events/percpu.h b/include/trace/events/percpu.h
> index df112a64f6c9..e989cefc0def 100644
> --- a/include/trace/events/percpu.h
> +++ b/include/trace/events/percpu.h
> @@ -6,15 +6,20 @@
>  #define _TRACE_PERCPU_H
>  
>  #include <linux/tracepoint.h>
> +#include <trace/events/mmflags.h>
>  
>  TRACE_EVENT(percpu_alloc_percpu,
>  
> -	TP_PROTO(bool reserved, bool is_atomic, size_t size,
> -		 size_t align, void *base_addr, int off, void __percpu *ptr),
> +	TP_PROTO(unsigned long call_site,
> +		 bool reserved, bool is_atomic, size_t size,
> +		 size_t align, void *base_addr, int off,
> +		 void __percpu *ptr, size_t bytes_alloc, gfp_t gfp_flags),

Don't we want to preserve the order and add the call_site at the end?
Trace events are not ABI, but if we don't have a strong reason to break it,
I'd preserve the old order.

Thanks!