On Tue, Sep 10, 2013 at 09:45:09AM +0900, Yasuaki Ishimatsu wrote: >(2013/09/02 12:45), Bob Liu wrote: >> Currently khugepaged will try to merge HPAGE_PMD_NR normal pages to a huge page >> which is allocated from the node of the first normal page, this policy is very >> rough and may affect userland applications. > >> Andrew Davidoff reported a related issue several days ago. > >Where is an original e-mail? >I tried to find original e-mail in my mailbox. But I cannot find it. > http://marc.info/?l=linux-mm&m=137701470529356&w=2 >Thanks, >Yasuaki Ishimatsu > >> >> Using "numactl --interleave=all ./test" to run the testcase, but the result >> wasn't not as expected. >> cat /proc/2814/numa_maps: >> 7f50bd440000 interleave:0-3 anon=51403 dirty=51403 N0=435 N1=435 N2=435 >> N3=50098 >> The end results showed that most pages are from Node3 instead of interleave >> among node0-3 which was unreasonable. >> >> This patch adds a more complicated policy. >> When searching HPAGE_PMD_NR normal pages, record which node those pages come >> from. Alway allocate hugepage from the node with the max record. If several >> nodes have the same max record, try to interleave among them. >> >> After this patch the result was as expected: >> 7f78399c0000 interleave:0-3 anon=51403 dirty=51403 N0=12723 N1=12723 N2=13235 >> N3=12722 >> >> The simple testcase is like this: >> #include<stdio.h> >> #include<stdlib.h> >> >> int main() { >> char *p; >> int i; >> int j; >> >> for (i=0; i < 200; i++) { >> p = (char *)malloc(1048576); >> printf("malloc done\n"); >> >> if (p == 0) { >> printf("Out of memory\n"); >> return 1; >> } >> for (j=0; j < 1048576; j++) { >> p[j] = 'A'; >> } >> printf("touched memory\n"); >> >> sleep(1); >> } >> printf("enter sleep\n"); >> while(1) { >> sleep(100); >> } >> } >> >> Reported-by: Andrew Davidoff <davidoff@xxxxxxxxx> >> Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx> >> --- >> mm/huge_memory.c | 50 +++++++++++++++++++++++++++++++++++++++++--------- >> 1 file changed, 41 insertions(+), 9 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index 7448cf9..86c7f0d 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -2144,7 +2144,33 @@ static void khugepaged_alloc_sleep(void) >> msecs_to_jiffies(khugepaged_alloc_sleep_millisecs)); >> } >> >> +static int khugepaged_node_load[MAX_NUMNODES]; >> #ifdef CONFIG_NUMA >> +static int last_khugepaged_target_node = NUMA_NO_NODE; >> +static int khugepaged_find_target_node(void) >> +{ >> + int i, target_node = 0, max_value = 1; >> + >> + /* find first node with most normal pages hit */ >> + for (i = 0; i < MAX_NUMNODES; i++) >> + if (khugepaged_node_load[i] > max_value) { >> + max_value = khugepaged_node_load[i]; >> + target_node = i; >> + } >> + >> + /* do some balance if several nodes have the same hit number */ >> + if (target_node <= last_khugepaged_target_node) { >> + for (i = last_khugepaged_target_node + 1; i < MAX_NUMNODES; i++) >> + if (max_value == khugepaged_node_load[i]) { >> + target_node = i; >> + break; >> + } >> + } >> + >> + last_khugepaged_target_node = target_node; >> + return target_node; >> +} >> + >> static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) >> { >> if (IS_ERR(*hpage)) { >> @@ -2178,9 +2204,8 @@ static struct page >> * mmap_sem in read mode is good idea also to allow greater >> * scalability. >> */ >> - *hpage = alloc_hugepage_vma(khugepaged_defrag(), vma, address, >> - node, __GFP_OTHER_NODE); >> - >> + *hpage = alloc_pages_exact_node(node, alloc_hugepage_gfpmask( >> + khugepaged_defrag(), __GFP_OTHER_NODE), HPAGE_PMD_ORDER); >> /* >> * After allocating the hugepage, release the mmap_sem read lock in >> * preparation for taking it in write mode. >> @@ -2196,6 +2221,11 @@ static struct page >> return *hpage; >> } >> #else >> +static int khugepaged_find_target_node(void) >> +{ >> + return 0; >> +} >> + >> static inline struct page *alloc_hugepage(int defrag) >> { >> return alloc_pages(alloc_hugepage_gfpmask(defrag, 0), >> @@ -2405,6 +2435,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, >> if (pmd_trans_huge(*pmd)) >> goto out; >> >> + memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); >> pte = pte_offset_map_lock(mm, pmd, address, &ptl); >> for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; >> _pte++, _address += PAGE_SIZE) { >> @@ -2421,12 +2452,11 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, >> if (unlikely(!page)) >> goto out_unmap; >> /* >> - * Chose the node of the first page. This could >> - * be more sophisticated and look at more pages, >> - * but isn't for now. >> + * Chose the node of most normal pages hit, record this >> + * informaction to khugepaged_node_load[] >> */ >> - if (node == NUMA_NO_NODE) >> - node = page_to_nid(page); >> + node = page_to_nid(page); >> + khugepaged_node_load[node]++; >> VM_BUG_ON(PageCompound(page)); >> if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) >> goto out_unmap; >> @@ -2441,9 +2471,11 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, >> ret = 1; >> out_unmap: >> pte_unmap_unlock(pte, ptl); >> - if (ret) >> + if (ret) { >> + node = khugepaged_find_target_node(); >> /* collapse_huge_page will return with the mmap_sem released */ >> collapse_huge_page(mm, address, hpage, vma, node); >> + } >> out: >> return ret; >> } >> > > >-- >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> -- 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>