Currently the heap has a fixed housekeeping factor of 16, which means
1/16 of the heap is reserved for list nodes. But this is not enough when
there are many small allocations; in the worst case, 1/3 of the heap is
needed for list nodes (32 byte heap_node for each 64 byte allocation).
This has caused allocation failures on some platforms.
Let's avoid trying to guess the best ratio. Instead, allocate more nodes
as needed. To avoid recursion, the nodes are permanent allocations. So
to minimize fragmentation, allocate them in small batches from the end
of the last free space node. Bootstrap the free space list by embedding
one node in the heap control struct.
Some error paths are avoided because the nodes are allocated up front.
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250617032306.1494528-3-samuel.holland@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This change adds a simple implementation of sbi_aligned_alloc(), for future use
in allocating aligned memory for SMMTT tables.
Signed-off-by: Gregor Haas <gregorhaas1997@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
In the next commit, we'll add a new sbi_memalign() function. In order to
allocate aligned memory, we'll sometimes need to allocate from the middle of a
heap block, effectively splitting it in two. Allocating from the beginning of a
heap block in the nonaligned case more closely matches this behavior, reducing
the complexity of understanding the heap implementation.
Signed-off-by: Gregor Haas <gregorhaas1997@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
The upcoming SMMTT implementation will require some larger contiguous memory
regions for the memory tracking tables. We plan to specify the memory region
for these tables as a reserved-memory node in the device tree, and then
dynamically allocate individual tables out of this region. These changes to the
SBI heap allocator will allow us to explicitly create and allocate from a
dedicated heap tied to the table memory region.
Signed-off-by: Gregor Haas <gregorhaas1997@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Previous patch introduced a change that using hart count as the default
number of tlb entries in the fifo. This makes the default tlb fifo size
grow in square with the number of harts. So the default heap size is
not enough to allocate tlb fifo when the hart count is big.
Fixes: 52fd64b ("platform: Uses hart count as the default size of tlb info")
Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
We provide simple heap allocator to manage the heap space provided
by OpenSBI firmware and platform.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
