Messages in this thread Patch in this message | | | Date | Tue, 15 Dec 2020 23:36:23 +0200 | From | Mike Rapoport <> | Subject | Re: [PATCH] mm: cma: allocate cma areas bottom-up |
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Hi Roman,
On Tue, Dec 15, 2020 at 11:36:15AM -0800, Roman Gushchin wrote: > Currently cma areas without a fixed base address are allocated > close to the end of the node. This placement is sub-optimal because > of how the compaction works: it effectively moves pages into > the cma area. In particular, it often brings in hot executable pages, > even if there is a plenty of free memory on the machine. > This results in more cma allocation failures. > > Instead let's place cma areas close to the beginning of a node. > Cma first tries to start with highmem_start, so we shouldn't mess > up with DMA32. In this case the compaction will help to free cma > areas, resulting in better cma allocation success rates. > > Signed-off-by: Roman Gushchin <guro@fb.com> > --- > include/linux/memblock.h | 5 +++-- > mm/cma.c | 4 ++-- > mm/memblock.c | 26 +++++++++++++++----------- > 3 files changed, 20 insertions(+), 15 deletions(-) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index 9c5cc95c7cee..698188066450 100644 > --- a/include/linux/memblock.h > +++ b/include/linux/memblock.h > @@ -384,8 +384,9 @@ static inline int memblock_get_region_node(const struct memblock_region *r) > phys_addr_t memblock_phys_alloc_range(phys_addr_t size, phys_addr_t align, > phys_addr_t start, phys_addr_t end); > phys_addr_t memblock_alloc_range_nid(phys_addr_t size, > - phys_addr_t align, phys_addr_t start, > - phys_addr_t end, int nid, bool exact_nid); > + phys_addr_t align, phys_addr_t start, > + phys_addr_t end, int nid, bool exact_nid, > + bool bottom_up); > phys_addr_t memblock_phys_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid); > > static inline phys_addr_t memblock_phys_alloc(phys_addr_t size, > diff --git a/mm/cma.c b/mm/cma.c > index 20c4f6f40037..1b42be6d059b 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -332,13 +332,13 @@ int __init cma_declare_contiguous_nid(phys_addr_t base, > */ > if (base < highmem_start && limit > highmem_start) { > addr = memblock_alloc_range_nid(size, alignment, > - highmem_start, limit, nid, true); > + highmem_start, limit, nid, true, true); > limit = highmem_start; > } > > if (!addr) { > addr = memblock_alloc_range_nid(size, alignment, base, > - limit, nid, true); > + limit, nid, true, true); > if (!addr) { > ret = -ENOMEM; > goto err; > diff --git a/mm/memblock.c b/mm/memblock.c > index b8b7be0561c4..c334b401fe16 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -272,6 +272,7 @@ __memblock_find_range_top_down(phys_addr_t start, phys_addr_t end, > * %MEMBLOCK_ALLOC_ACCESSIBLE > * @nid: nid of the free area to find, %NUMA_NO_NODE for any node > * @flags: pick from blocks based on memory attributes > + * @bottom_up: force bottom-up allocation
Why wouldn't you use memblock_set_bottom_up() around the allocations in CMA, e.g.
bool bottom_up = memblock_bottom_up();
if (!bottom_up) memblock_set_bottom_up(true);
/* allocate memory */
memblock_set_bottom_up(bottom_up);
> * > * Find @size free area aligned to @align in the specified range and node. > * > @@ -289,7 +290,8 @@ __memblock_find_range_top_down(phys_addr_t start, phys_addr_t end,
-- Sincerely yours, Mike.
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