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Date:   Fri, 29 Apr 2022 16:05:14 +0200
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To:     Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc:     Marco Elver <elver@google.com>,
        Matthew WilCox <willy@infradead.org>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Roman Gushchin <roman.gushchin@linux.dev>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <20220414085727.643099-1-42.hyeyoo@gmail.com>
 <20220414085727.643099-15-42.hyeyoo@gmail.com>
From:   Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v2 14/23] mm/slab_common: print cache name in tracepoints
In-Reply-To: <20220414085727.643099-15-42.hyeyoo@gmail.com>
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On 4/14/22 10:57, Hyeonggon Yoo wrote:
> Print cache name in tracepoints. If there is no corresponding cache
> (kmalloc in SLOB or kmalloc_large_node), use KMALLOC_{,LARGE_}NAME
> macro.
> 
> Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>

Regarding tracepoints, I'm not sure it's a good idea to unify kmalloc and
kmem_cache_alloc. I think the common use case is to trace kmalloc as there
are many different callers, and then I'm not interested in kmem_cache_alloc
callers much.

What I would suggest instead is:
- drop the _node versions, add node to normal versions
- drop the kmem_alloc EVENT_CLASS, as kmalloc is different enough from
kmem_cache_alloc (see next points), define separately as TRACE_EVENT().
- printing cache_name makes sense to add for kmem_cache_alloc (also allows
filtering events) but not for kmalloc.
- kmem_cache_alloc with name can then drop the bytes_req, bytes_alloc as
they are fixed for given name (and can be read from slabinfo).

Not using a common tracepoint will prevent some later unifications/cleanup
(patch 21?), but hopefully not too much?