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. 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
