On Sat, Jan 14, 2023 at 09:23:23PM +0800, Zhang Boyang wrote: > When grub_memalign() encounters out-of-memory, it will try > grub_mm_add_region_fn() to request more memory from system firmware. > However, it doesn't preallocate memory space for future allocation > requests. In extreme cases, it requires one call to > grub_mm_add_region_fn() for each memory allocation request. This can be > very slow. > > This patch introduces GRUB_MM_HEAP_GROW_EXTRA, the minimal heap growth > granularity. The new region size is now set to the bigger one of its > original value and GRUB_MM_HEAP_GROW_EXTRA. Thus, it will result in some > memory space preallocated if current allocations request is small. > > The value of GRUB_MM_HEAP_GROW_EXTRA is set to 1MB. If this value is > smaller, the cost of small memory allocations will be higher. If this > value is larger, more memory will be wasted and it might cause > out-of-memory on machines with small amount of RAM. > > Signed-off-by: Zhang Boyang <zhangboyang...@gmail.com> > --- > grub-core/kern/mm.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c > index 278756dea..4e220bbff 100644 > --- a/grub-core/kern/mm.c > +++ b/grub-core/kern/mm.c > @@ -123,6 +123,9 @@ > /* The size passed to grub_mm_add_region_fn() is aligned up by this value. */ > #define GRUB_MM_HEAP_GROW_ALIGN 4096 > > +/* Minimal heap growth granularity when existing heap space is exhausted. */ > +#define GRUB_MM_HEAP_GROW_EXTRA 0x100000 > + > grub_mm_region_t grub_mm_base; > grub_mm_add_region_func_t grub_mm_add_region_fn; > > @@ -471,6 +474,9 @@ grub_memalign (grub_size_t align, grub_size_t size) > if (grub_add (size + align, GRUB_MM_MGMT_OVERHEAD, &grow)) > goto fail; > > + /* Preallocate some extra space if heap growth is small. */ > + grow = grub_max (grow, GRUB_MM_HEAP_GROW_EXTRA); > + > /* Align up heap growth to make it friendly to CPU/MMU. */ > if (grow > ~(grub_size_t) (GRUB_MM_HEAP_GROW_ALIGN - 1)) > goto fail;
Reviewed-by: Patrick Steinhardt <p...@pks.im>
Thanks for both patches!
Patrick
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