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Message-ID: <768859b4-5cae-4e16-1d9c-8b78a7b36ced@openvz.org>
Date:   Tue, 17 May 2022 06:49:04 +0300
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Subject: Re: [PATCH] tracing: add ACCOUNT flag for allocations from marked
 slab caches
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To:     Roman Gushchin <roman.gushchin@linux.dev>,
        Vlastimil Babka <vbabka@suse.cz>
Cc:     Shakeel Butt <shakeelb@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Christoph Lameter <cl@linux.com>, kernel@openvz.org,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>
References: <1fd21e25-b095-e055-fc2e-abda640a0575@openvz.org>
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 <8eccb3bc-e6b1-354b-e1de-bd3d896dcb35@suse.cz> <YoLLcFFi5UXFEIYg@carbon>
From:   Vasily Averin <vvs@openvz.org>
In-Reply-To: <YoLLcFFi5UXFEIYg@carbon>
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On 5/17/22 01:08, Roman Gushchin wrote:
> On Mon, May 16, 2022 at 11:41:27PM +0200, Vlastimil Babka wrote:
>> On 5/16/22 21:10, Shakeel Butt wrote:
>>> On Mon, May 16, 2022 at 11:53 AM Vasily Averin <vvs@openvz.org> wrote:
>>>>  {
>>>>         void *ret = slab_alloc(cachep, lru, flags, cachep->object_size, _RET_IP_);
>>>>
>>>> +       if (cachep->flags & SLAB_ACCOUNT)
>>>
>>> Should this 'if' be unlikely() or should we trace cachep->flags
>>> explicitly to avoid this branch altogether?
>>
>> Hm I think ideally the tracepoint accepts cachep instead of current
>> cachep->*size parameters and does the necessary extraction and
>> modification in its fast_assign.
> 
> +1 for fast_assign
> 
> Changing flags just for tracing looks a bit excessive.

At the kmem_cache_alloc and kmem_alloc use the same tracing template.
Ok, I'll try to redesign this.