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Thu, 25 May 2023 12:05:28 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id jK1RDghPb2TwKgAAMHmgww (envelope-from ); Thu, 25 May 2023 12:05:28 +0000 Date: Thu, 25 May 2023 13:59:20 +0200 From: David Sterba To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: David Sterba , Christoph Lameter , David Rientjes , Pekka Enberg , Vlastimil Babka , Andrew Morton , Joonsoo Kim , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Roman Gushchin Subject: Re: [PATCH] mm/slab: add new flag SLAB_NO_MERGE to avoid merging per slab Message-ID: <20230525115920.GG30909@suse.cz> Reply-To: dsterba@suse.cz References: <20230524101748.30714-1-dsterba@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Rspamd-Queue-Id: 3F9E41C0082 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 53haswe7x8k9r9wqym7r1kg56kwcctze X-HE-Tag: 1685016330-677796 X-HE-Meta: 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 NHUjvure EiQ3Uo6A9BrQg2ZS5+/ank2kk1kBPkEJDeLSSVlo///S4Q3VXvsF6ldaAyZHjnwBzTO4pWDAOw6R0HpQ25q/dWUBifY8lCJmtro+rsw91w3qWJ4YWtspjrc8FQil4xNYcKGUrJSOwwwRbSy4PhALcGoBNLSgNRxhRhw3gJ6WfuBQ6PIgMHn6C9mMalIve36DKW6I08V7Hh5p7IammMffDa4CVTv5GR7xuTsnv7qZ7l6FBYnFpDeSS20kI83uhtu454IovvW0UIqrfeoPBLpkMV9fZ+pZMLfFpnHotHhnSGUQDcCGdTXjKRi8v2SbjOVyOJBrzz7s0Zdh6a380B9eUqAps9eAF9Y1lKx8RSBLKTKs8n+pigjs0TV+EV6ezrxlyTPLa6sASlWKR9EvzM9ghg5uVS5C3V0YEACc0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, May 24, 2023 at 09:56:02PM +0900, Hyeonggon Yoo wrote: > On Wed, May 24, 2023 at 12:17:48PM +0200, David Sterba wrote: > > Add a flag that allows to disable merging per slab. This can be used for > > more fine grained control over the caches or for debugging builds where > > separate slabs can verify that no objects leak. > > The slab_nomerge boot option is too coarse and would need to be enabled > > on all testing hosts. > > There is no users nor interface to set this flag, I guess you're going > to use it by modifying source code, when debugging? An example usage --- a/fs/btrfs/fs.h +++ b/fs/btrfs/fs.h @@ -12,6 +12,12 @@ #include "async-thread.h" #include "block-rsv.h" +#ifdef CONFIG_BTRFS_DEBUG +#define SLAB_DEBUG_NO_MERGE 0 +#else +#define SLAB_DEBUG_NO_MERGE SLAB_NO_MERGE +#endif + #define BTRFS_MAX_EXTENT_SIZE SZ_128M #define BTRFS_OLDEST_GENERATION 0ULL --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -5049,7 +5049,7 @@ int __init btrfs_ctree_init(void) { btrfs_path_cachep = kmem_cache_create("btrfs_path", sizeof(struct btrfs_path), 0, - SLAB_MEM_SPREAD, NULL); + SLAB_MEM_SPREAD | SLAB_DEBUG_NO_MERGE, NULL); if (!btrfs_path_cachep) return -ENOMEM; return 0; --- and this will be a permanent change, not added as needed. > Does introducing new slub_debug option (i.e. slub_debug=N,pid_namespace) > work for your use case? (there are some boot-time slub_debug options described in > Documentation/mm/slub.rst) I'd like to keep boot parameters unchanged, the testing setups are different, physical, local VM, hosted. For the same reason the config option CONFIG_SLUB_DEBUG_ON=y is very convenient.