Hi Yinghai, The patch fails compilation as below: mm/page_alloc.c:151: error: initializer element is not constant mm/page_alloc.c:151: error: expected ‘,’ or ‘;’ before ‘__attribute__’ On IA64, HUGETLB_PAGE_ORDER has dependency on variable hpage_shift. # define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) # define HPAGE_SHIFT hpage_shift And hpage_shift could be changed by early parameter "hugepagesz". So seems will still need to keep function set_pageblock_order(). Thanks! Gerry On 2012-7-1 4:15, Yinghai Lu wrote: > On Sat, Jun 30, 2012 at 2:07 AM, Jiang Liu <jiang.liu@xxxxxxxxxx> wrote: >> From: Xishi Qiu <qiuxishi@xxxxxxxxxx> >> >> On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium, >> pageblock_order is a variable with default value of 0. It's set to the right >> value by set_pageblock_order() in function free_area_init_core(). >> >> But pageblock_order may be used by sparse_init() before free_area_init_core() >> is called along path: >> sparse_init() >> ->sparse_early_usemaps_alloc_node() >> ->usemap_size() >> ->SECTION_BLOCKFLAGS_BITS >> ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * >> NR_PAGEBLOCK_BITS) >> >> The uninitialized pageblock_size will cause memory wasting because usemap_size() >> returns a much bigger value then it's really needed. >> >> For example, on an Itanium platform, >> sparse_init() pageblock_order=0 usemap_size=24576 >> free_area_init_core() before pageblock_order=0, usemap_size=24576 >> free_area_init_core() after pageblock_order=12, usemap_size=8 >> >> That means 24K memory has been wasted for each section, so fix it by calling >> set_pageblock_order() from sparse_init(). >> > > can you check attached patch? > > That will kill more lines code instead. > > Thanks > > Yinghai -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>