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Mon, 04 Dec 2023 16:53:46 -0800 (PST) MIME-Version: 1.0 References: <20231203001501.126339-1-sxwjean@me.com> <20231203001501.126339-4-sxwjean@me.com> In-Reply-To: <20231203001501.126339-4-sxwjean@me.com> From: Hyeonggon Yoo <42.hyeyoo@gmail.com> Date: Tue, 5 Dec 2023 09:53:34 +0900 Message-ID: Subject: Re: [PATCH v2 3/3] mm/slub: correct the default value of slub_min_objects in doc To: sxwjean@me.com Cc: vbabka@suse.cz, cl@linux.com, linux-mm@kvack.org, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, roman.gushchin@linux.dev, corbet@lwn.net, keescook@chromium.org, arnd@arndb.de, akpm@linux-foundation.org, gregkh@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Xiongwei Song Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: aqo3efz3jq8gqtpgrwc4aosi8cjw3zme X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 4CB8B4000B X-Rspam-User: X-HE-Tag: 1701737627-237456 X-HE-Meta: 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 e8NCpqGh 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 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: List-Subscribe: List-Unsubscribe: On Sun, Dec 3, 2023 at 9:16=E2=80=AFAM wrote: > > From: Xiongwei Song > > There is no a value assigned to slub_min_objects by default, it always > is 0 that is initialized by compiler if no assigned value by command line= . > min_objects is calculated based on processor numbers in calculate_order()= . > For more details, see commit 9b2cd506e5f2 ("slub: Calculate min_objects > based on number of processors.") > > Signed-off-by: Xiongwei Song While slub_min_objects equals zero by default, 'min_objects' overrides it t= o 4 * (fls(nr_cpus) + 1) when not set. so when slub_min_objects is not set, it would be equal to or higher than 4. I'm not sure this level of implementation detail is worth documenting. Also, I think patch 2 should update Documentation/mm/slub.rst too. (slub_$param -> slab_param) > --- > Documentation/mm/slub.rst | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/Documentation/mm/slub.rst b/Documentation/mm/slub.rst > index be75971532f5..1f4399581449 100644 > --- a/Documentation/mm/slub.rst > +++ b/Documentation/mm/slub.rst > @@ -150,7 +150,7 @@ list_lock once in a while to deal with partial slabs.= That overhead is > governed by the order of the allocation for each slab. The allocations > can be influenced by kernel parameters: > > -.. slub_min_objects=3Dx (default 4) > +.. slub_min_objects=3Dx (default 0) > .. slub_min_order=3Dx (default 0) > .. slub_max_order=3Dx (default 3 (PAGE_ALLOC_COSTLY_ORDER)) > > -- > 2.34.1 >