The kernel fills new allocated (huge) pages with zeros.
DPDK just has to touch the pages to trigger the allocation.
Signed-off-by: Zhihong Wang
---
lib/librte_eal/linuxapp/eal/eal_memory.c | 20 ++--
1 file changed, 6 insertions(+), 14 deletions(-)
diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
b/lib/librte_eal/linuxapp/eal/eal_memory.c
index 0de75cd..21a5146 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -399,8 +399,10 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl,
return -1;
}
+ /* map the segment, and populate page tables,
+* the kernel fills this segment with zeros */
virtaddr = mmap(vma_addr, hugepage_sz, PROT_READ | PROT_WRITE,
- MAP_SHARED, fd, 0);
+ MAP_SHARED | MAP_POPULATE, fd, 0);
if (virtaddr == MAP_FAILED) {
RTE_LOG(ERR, EAL, "%s(): mmap failed: %s\n", __func__,
strerror(errno));
@@ -410,7 +412,6 @@ map_all_hugepages(struct hugepage_file *hugepg_tbl,
if (orig) {
hugepg_tbl[i].orig_va = virtaddr;
- memset(virtaddr, 0, hugepage_sz);
}
else {
hugepg_tbl[i].final_va = virtaddr;
@@ -529,22 +530,16 @@ remap_all_hugepages(struct hugepage_file *hugepg_tbl,
struct hugepage_info *hpi)
old_addr = vma_addr;
- /* map new, bigger segment */
+ /* map new, bigger segment, and populate page tables,
+* the kernel fills this segment with zeros */
vma_addr = mmap(vma_addr, total_size,
- PROT_READ | PROT_WRITE, MAP_SHARED, fd,
0);
+ PROT_READ | PROT_WRITE, MAP_SHARED |
MAP_POPULATE, fd, 0);
if (vma_addr == MAP_FAILED || vma_addr != old_addr) {
RTE_LOG(ERR, EAL, "%s(): mmap failed: %s\n",
__func__, strerror(errno));
close(fd);
return -1;
}
-
- /* touch the page. this is needed because kernel
postpones mapping
-* creation until the first page fault. with this, we
pin down
-* the page and it is marked as used and gets into
process' pagemap.
-*/
- for (offset = 0; offset < total_size; offset +=
hugepage_sz)
- *((volatile uint8_t*) RTE_PTR_ADD(vma_addr,
offset));
}
/* set shared flock on the file. */
@@ -592,9 +587,6 @@ remap_all_hugepages(struct hugepage_file *hugepg_tbl,
struct hugepage_info *hpi)
}
}
- /* zero out the whole segment */
- memset(hugepg_tbl[page_idx].final_va, 0, total_size);
-
page_idx++;
}
--
2.5.0
