On 11/24/22 02:20, Roman Gushchin wrote: > On Mon, Nov 21, 2022 at 06:11:57PM +0100, Vlastimil Babka wrote: >> SLAB_RECLAIM_ACCOUNT caches allocate their slab pages with >> __GFP_RECLAIMABLE and can help against fragmentation by grouping pages >> by mobility, but on tiny systems mobility grouping is likely disabled >> anyway and ignoring SLAB_RECLAIM_ACCOUNT might instead lead to merging >> of caches that are made incompatible just by the flag. >> >> Thus with CONFIG_SLUB_TINY, make SLAB_RECLAIM_ACCOUNT ineffective. > > Hm, do you see disabling all kernel memory accounting functionality > with COFNIG_SLUB_TINY? I'd say yes. But in this case need to be consistent > and disable it alltogether. SLAB_RECLAIM_ACCOUNT is kinda misnomer these days, as the only thing it does is to add __GFP_RECLAIMABLE to cache's gfp flags for the page allocator's mobility grouping. I guess the "ACCOUNT" part comes from being counted towards SReclaimable (vs SUnreclaim) in /proc/meminfo. So currently SLUB_TINY has no effect on MEMCG_KMEM (which you probably meant). Using those two together has little sense and had I stumbled while making this series upon a code that would become complicated, I would have made SLUB_TINY disable MEMCG_KMEM, but that didn't happen so I left as is for now. > Thanks!
