On Tue, Nov 29, 2022 at 10:17:34PM +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, which may be > too slow if those requests are small (e.g. about 4KB).
s/, which may ... are small (e.g. about 4KB)./. This can be very slow./ > This patch introduces GRUB_MM_HEAP_GROW, the minimal heap growth s/GRUB_MM_HEAP_GROW/GRUB_MM_HEAP_GROW_EXTRA/ > granularity. The new region size is now set to the bigger one of > original value and GRUB_MM_HEAP_GROW. Thus, it will result in some > memory space preallocated if current allocations request is small. > > The value of GRUB_MM_HEAP_GROW 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 | 3 +++ > include/grub/mm_private.h | 3 +++ > 2 files changed, 6 insertions(+) > > diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c > index 973cb6b15..83c618c5b 100644 > --- a/grub-core/kern/mm.c > +++ b/grub-core/kern/mm.c > @@ -452,6 +452,9 @@ grub_memalign (grub_size_t align, grub_size_t size) > if (grub_add (bound, GRUB_MM_MAX_COST, &grow)) > goto fail; > > + /* Calculate optimal size of heap growth. */ > + grow = grub_max (grow, GRUB_MM_HEAP_GROW); This should be "if (grub_add (grow, GRUB_MM_HEAP_GROW, &grow))..." And it should happen before first grub_mm_add_region_fn() call. > /* Request additional pages, contiguous */ > count++; > > diff --git a/include/grub/mm_private.h b/include/grub/mm_private.h > index f212110e4..268fbf094 100644 > --- a/include/grub/mm_private.h > +++ b/include/grub/mm_private.h > @@ -104,6 +104,9 @@ typedef struct grub_mm_region > */ > #define GRUB_MM_MAX_COST 0x1000 > > +/* Minimal heap growth granularity when existing heap space is exhausted. */ > +#define GRUB_MM_HEAP_GROW 0x100000 Is 1 MiB enough? I think yes but prefer to double check... Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
