> -----Original Message----- > From: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> > Sent: Wednesday, December 6, 2023 8:23 AM > To: Song, Xiongwei <Xiongwei.Song@xxxxxxxxxxxxx> > Cc: sxwjean@xxxxxx; vbabka@xxxxxxx; cl@xxxxxxxxx; linux-mm@xxxxxxxxx; > penberg@xxxxxxxxxx; rientjes@xxxxxxxxxx; iamjoonsoo.kim@xxxxxxx; > roman.gushchin@xxxxxxxxx; corbet@xxxxxxx; keescook@xxxxxxxxxxxx; arnd@xxxxxxxx; > akpm@xxxxxxxxxxxxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 3/3] mm/slub: correct the default value of slub_min_objects in doc > > CAUTION: This email comes from a non Wind River email account! > Do not click links or open attachments unless you recognize the sender and know the content > is safe. > > On Tue, Dec 5, 2023 at 11:11 PM Song, Xiongwei > <Xiongwei.Song@xxxxxxxxxxxxx> wrote: > > > > Hi Hyeonggon, > > > > > -----Original Message----- > > > From: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> > > > Sent: Tuesday, December 5, 2023 8:54 AM > > > To: sxwjean@xxxxxx > > > Cc: vbabka@xxxxxxx; cl@xxxxxxxxx; linux-mm@xxxxxxxxx; penberg@xxxxxxxxxx; > > > rientjes@xxxxxxxxxx; iamjoonsoo.kim@xxxxxxx; roman.gushchin@xxxxxxxxx; > > > corbet@xxxxxxx; keescook@xxxxxxxxxxxx; arnd@xxxxxxxx; akpm@linux- > foundation.org; > > > gregkh@xxxxxxxxxxxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > Song, > > > Xiongwei <Xiongwei.Song@xxxxxxxxxxxxx> > > > Subject: Re: [PATCH v2 3/3] mm/slub: correct the default value of slub_min_objects in > doc > > > > > > On Sun, Dec 3, 2023 at 9:16 AM <sxwjean@xxxxxx> wrote: > > > > > > > > From: Xiongwei Song <xiongwei.song@xxxxxxxxxxxxx> > > > > > > > > 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 <xiongwei.song@xxxxxxxxxxxxx> > > > > > > While slub_min_objects equals zero by default, 'min_objects' overrides it to > > > 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. > > > > commit 9b2cd506e5f2 ("slub: Calculate min_objects based on number of processors.") > > has already given "processors min_objects" pair, do we really need to document > > the specific detail? > > No, I don't think it needs to be documented, but neither do I think > "slub_min_objects is > 0 by default" is correctly documented... > > > > Also, I think patch 2 should update Documentation/mm/slub.rst too. > > > (slub_$param -> slab_param) > > I think people can know slub_$params are still supported by > > Documentation/mm/slub.rst, so we don't need to say the info again in > > this file. Is it better to do so just before removing slub_$params > > completely? > > If we're deprecating and planning to drop slub_$params in the future, > IMHO it'd be less confusing if we change it now, rather than > when removing slub_$params completely (probably 10 years later)? Ok, sure. Will update in next version. Regards, Xiongwei > > Thanks, > Hyeonggon > > > > > --- > > > > 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=x (default 4) > > > > +.. slub_min_objects=x (default 0) > > > > .. slub_min_order=x (default 0) > > > > .. slub_max_order=x (default 3 (PAGE_ALLOC_COSTLY_ORDER)) > > > > > > > > -- > > > > 2.34.1 > > > >