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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.id@gmail.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'