> -----Original Message----- > From: Vlastimil Babka <vbabka@xxxxxxx> > Sent: Monday, November 27, 2023 8:03 PM > To: Song, Xiongwei <Xiongwei.Song@xxxxxxxxxxxxx>; sxwjean@xxxxxx; > 42.hyeyoo@xxxxxxxxx; linux-mm@xxxxxxxxx > Cc: cl@xxxxxxxxx; penberg@xxxxxxxxxx; rientjes@xxxxxxxxxx; iamjoonsoo.kim@xxxxxxx; > akpm@xxxxxxxxxxxxxxxxxxxx; roman.gushchin@xxxxxxxxx; corbet@xxxxxxx; linux- > doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v2] Documentation: kernel-parameters: remove slab_max_order and > noaliencache > > 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 11/26/23 08:25, Song, Xiongwei wrote: > > Hi Vlastimil, > > > >> -----Original Message----- > >> From: Vlastimil Babka <vbabka@xxxxxxx> > >> Sent: Friday, November 24, 2023 7:24 PM > >> To: sxwjean@xxxxxx; 42.hyeyoo@xxxxxxxxx; linux-mm@xxxxxxxxx > >> Cc: cl@xxxxxxxxx; penberg@xxxxxxxxxx; rientjes@xxxxxxxxxx; iamjoonsoo.kim@xxxxxxx; > >> akpm@xxxxxxxxxxxxxxxxxxxx; roman.gushchin@xxxxxxxxx; corbet@xxxxxxx; linux- > >> doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Song, Xiongwei > >> <Xiongwei.Song@xxxxxxxxxxxxx> > >> Subject: Re: [PATCH v2] Documentation: kernel-parameters: remove slab_max_order and > >> noaliencache > >> > >> > >> On 11/22/23 15:36, sxwjean@xxxxxx wrote: > >> > From: Xiongwei Song <xiongwei.song@xxxxxxxxxxxxx> > >> > > >> > Since slab allocator has already been removed. There is no users about > >> > slab_max_order and noaliencache, so let's remove them. > >> > > >> > Signed-off-by: Xiongwei Song <xiongwei.song@xxxxxxxxxxxxx> > >> > --- > >> > v2: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx> suggested that noaliencache should be > >> > removed too. Here adding this change. The patch is based on [1]. > >> > > >> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git/log/?h=slab- > remove- > >> slab-v2r1 > >> > > >> > v1: https://lore.kernel.org/linux-mm/20231120091214.150502-1- > >> sxwjean@xxxxxx/T/#m55ebb45851bc86d650baf65dfe8296d33c5b1126 > >> > --- > >> > Documentation/admin-guide/kernel-parameters.txt | 10 ---------- > >> > 1 file changed, 10 deletions(-) > >> > > >> > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin- > >> guide/kernel-parameters.txt > >> > index 65731b060e3f..d56a5beefe24 100644 > >> > --- a/Documentation/admin-guide/kernel-parameters.txt > >> > +++ b/Documentation/admin-guide/kernel-parameters.txt > >> > @@ -3740,10 +3740,6 @@ > >> > no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces > >> > kernel to use 4-level paging instead. > >> > > >> > - noaliencache [MM, NUMA, SLAB] Disables the allocation of alien > >> > - caches in the slab allocator. Saves per-node memory, > >> > - but will impact performance. > >> > >> No question about this one, can be deleted. > >> > >> > - > >> > noalign [KNL,ARM] > >> > > >> > noaltinstr [S390] Disables alternative instructions patching > >> > @@ -5887,12 +5883,6 @@ > >> > own. > >> > For more information see Documentation/mm/slub.rst. > >> > > >> > - slab_max_order= [MM, SLAB] > >> > - Determines the maximum allowed order for slabs. > >> > - A high setting may cause OOMs due to memory > >> > - fragmentation. Defaults to 1 for systems with > >> > - more than 32MB of RAM, 0 otherwise. > >> > >> I think here we should consider the long-term plan first. It's a bit > >> unfortunate (in hindsight) SLUB brought its own prefix of parameters, even > >> if some became interchangeable aliases later (slab/slub_nomerge), some not. > >> I think it would be best to unify them, and consider the string "slub" an > >> implementation detail of the general "slab allocator" term going forward. > >> > >> So what I'd propose is that we change all parameters to accept a > >> "slab_$param" as a primary and documented name (and the description can > >> contain just [MM] tag, no [SLAB] or [SLUB] needed), with "slub_$param" is > >> also accepted as an alias where it exists today, and there's just a note > >> that the slub_$param name is also accepted in the description of the > >> canonical parameter, not in a separate description. Then maybe in a few > >> years we can mark the old names as deprecated and start issuing low-key > >> warnings (while still accepting them), and in 10 years maybe remove them > >> completely. Thoughts? > > > > Sorry, I didn't know the SLUB history, thanks for the comments and proposal. > > > > Did you mean the rough diff below? > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin- > guide/kernel-parameters.txt > > index 65731b060e3f..db6d2ebe7c7d 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -5871,10 +5871,12 @@ > > slram= [HW,MTD] > > > > slab_merge [MM] > > + slub_merge [MM] > > Enable merging of slabs with similar size when the > > kernel is built without CONFIG_SLAB_MERGE_DEFAULT. > > I'd hope the result look more like this, so the duplicate names are not > so prominent. > > slab_merge [MM] > Enable merging of slabs with similar size when the > kernel is built without CONFIG_SLAB_MERGE_DEFAULT. > (slub_merge also accepted as an alias) > > Note that it's not just a Documentation change anymore, as many of the > parameters don't have the slab_ variants yet wired up. Ok, thanks. Will create a patch for it. Regards, Xiongwei > > > > > slab_nomerge [MM] > > + slub_nomerge [MM] > > Disable merging of slabs with similar size. May be > > necessary if there is some reason to distinguish > > allocs to different slabs, especially in hardened > > @@ -5887,12 +5889,6 @@ > > own. > > For more information see Documentation/mm/slub.rst. > > > > - slab_max_order= [MM, SLAB] > > - Determines the maximum allowed order for slabs. > > - A high setting may cause OOMs due to memory > > - fragmentation. Defaults to 1 for systems with > > - more than 32MB of RAM, 0 otherwise. > > - > > slub_debug[=options[,slabs][;[options[,slabs]]...] [MM, SLUB] > > Enabling slub_debug allows one to determine the > > culprit if slab objects become corrupted. Enabling > > @@ -5901,13 +5897,15 @@ > > last alloc / free. For more information see > > Documentation/mm/slub.rst. > > > > - slub_max_order= [MM, SLUB] > > + slab_max_order= [MM] > > + slub_max_order= [MM] > > Determines the maximum allowed order for slabs. > > A high setting may cause OOMs due to memory > > fragmentation. For more information see > > Documentation/mm/slub.rst. > > > > - slub_min_objects= [MM, SLUB] > > + slab_min_objects= [MM] > > + slub_min_objects= [MM] > > The minimum number of objects per slab. SLUB will > > increase the slab order up to slub_max_order to > > generate a sufficiently large slab able to contain > > @@ -5916,18 +5914,12 @@ > > and the less frequently locks need to be acquired. > > For more information see Documentation/mm/slub.rst. > > > > - slub_min_order= [MM, SLUB] > > + slub_min_order= [MM] > > + slab_min_order= [MM] > > Determines the minimum page order for slabs. > > Must be > > lower than slub_max_order. > > For more information see Documentation/mm/slub.rst. > > > > - slub_merge [MM, SLUB] > > - Same with slab_merge. > > - > > - slub_nomerge [MM, SLUB] > > - Same with slab_nomerge. This is supported for > > legacy. > > - See slab_nomerge for more information. > > - > > smart2= [HW] > > Format: <io1>[,<io2>[,...,<io8>]] > > > > If so I think we should use slab_¶m in mm/slub.c. When hitting "slub_$param" > > we need to assign the value to "slab_¶m" like "slab_nomerge", right? > > > > Regards, > > Xiongwei
