On 5/22/2023 1:41 PM, Fengnan Chang wrote:
Under legacy mode, if the number of continuous memsegs greater
than RTE_MAX_MEMSEG_PER_LIST, eal init will failed even though
another memseg list is empty, because only one memseg list used
to check in remap_needed_hugepages.
Fix this by add a argment indicate how many pages mapped in
remap_segment, remap_segment try to mapped most pages it can, if
exceed it's capbility, remap_needed_hugepages will continue to
map other left pages.

For example:
hugepage configure:
cat /sys/devices/system/node/node*/hugepages/hugepages-2048kB/nr_hugepages
10241
10239

startup log:
EAL: Detected memory type: socket_id:0 hugepage_sz:2097152
EAL: Detected memory type: socket_id:1 hugepage_sz:2097152
EAL: Creating 4 segment lists: n_segs:8192 socket_id:0 hugepage_sz:2097152
EAL: Creating 4 segment lists: n_segs:8192 socket_id:1 hugepage_sz:2097152
EAL: Requesting 13370 pages of size 2MB from socket 0
EAL: Requesting 7110 pages of size 2MB from socket 1
EAL: Attempting to map 14220M on socket 1
EAL: Allocated 14220M on socket 1
EAL: Attempting to map 26740M on socket 0
EAL: Could not find space for memseg. Please increase 32768 and/or 65536 in
configuration.
EAL: Couldn't remap hugepage files into memseg lists
EAL: FATAL: Cannot init memory
EAL: Cannot init memory

Signed-off-by: Fengnan Chang <changfeng...@bytedance.com>
Signed-off-by: Lin Li <lilint...@bytedance.com>
---
  lib/eal/linux/eal_memory.c | 33 +++++++++++++++++++++------------
  1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/lib/eal/linux/eal_memory.c b/lib/eal/linux/eal_memory.c
index 60fc8cc6ca..b2e6453fbe 100644
--- a/lib/eal/linux/eal_memory.c
+++ b/lib/eal/linux/eal_memory.c
@@ -657,12 +657,12 @@ unmap_unneeded_hugepages(struct hugepage_file *hugepg_tbl,
  }
static int
-remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
+remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end, int 
*mapped_seg_len)
  {
        struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
        struct rte_memseg_list *msl;
        struct rte_fbarray *arr;
-       int cur_page, seg_len;
+       int cur_page, seg_len, cur_len;
        unsigned int msl_idx;
        int ms_idx;
        uint64_t page_sz;
@@ -692,8 +692,9 @@ remap_segment(struct hugepage_file *hugepages, int 
seg_start, int seg_end)
/* leave space for a hole if array is not empty */
                empty = arr->count == 0;
+               cur_len = RTE_MIN((unsigned int)seg_len, arr->len - arr->count 
- (empty ? 0 : 1));
                ms_idx = rte_fbarray_find_next_n_free(arr, 0,
-                               seg_len + (empty ? 0 : 1));
+                               cur_len + (empty ? 0 : 1));
/* memseg list is full? */
                if (ms_idx < 0)
@@ -704,12 +705,12 @@ remap_segment(struct hugepage_file *hugepages, int 
seg_start, int seg_end)
                 */
                if (!empty)
                        ms_idx++;
+               *mapped_seg_len = cur_len;
                break;
        }
        if (msl_idx == RTE_MAX_MEMSEG_LISTS) {
-               RTE_LOG(ERR, EAL, "Could not find space for memseg. Please increase 
%s and/or %s in configuration.\n",
-                               RTE_STR(RTE_MAX_MEMSEG_PER_TYPE),
-                               RTE_STR(RTE_MAX_MEM_MB_PER_TYPE));
+               RTE_LOG(ERR, EAL, "Could not find space for memseg. Please increase 
RTE_MAX_MEMSEG_PER_LIST "
+                               "RTE_MAX_MEMSEG_PER_TYPE and/or 
RTE_MAX_MEM_MB_PER_TYPE in configuration.\n");
                return -1;
        }
@@ -725,6 +726,8 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
                void *addr;
                int fd;
+ if (cur_page - seg_start == *mapped_seg_len)
+                       break;
                fd = open(hfile->filepath, O_RDWR);
                if (fd < 0) {
                        RTE_LOG(ERR, EAL, "Could not open '%s': %s\n",
@@ -986,7 +989,7 @@ prealloc_segments(struct hugepage_file *hugepages, int 
n_pages)
  static int
  remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
  {
-       int cur_page, seg_start_page, new_memseg, ret;
+       int cur_page, seg_start_page, new_memseg, ret, mapped_seg_len = 0;
seg_start_page = 0;
        for (cur_page = 0; cur_page < n_pages; cur_page++) {
@@ -1023,21 +1026,27 @@ remap_needed_hugepages(struct hugepage_file *hugepages, 
int n_pages)
                        /* if this isn't the first time, remap segment */
                        if (cur_page != 0) {
                                ret = remap_segment(hugepages, seg_start_page,
-                                               cur_page);
+                                               cur_page, &mapped_seg_len);
                                if (ret != 0)
                                        return -1;
                        }
+                       cur_page = seg_start_page + mapped_seg_len;
                        /* remember where we started */
                        seg_start_page = cur_page;
+                       mapped_seg_len = 0;
                }
                /* continuation of previous memseg */
        }
        /* we were stopped, but we didn't remap the last segment, do it now */
        if (cur_page != 0) {
-               ret = remap_segment(hugepages, seg_start_page,
-                               cur_page);
-               if (ret != 0)
-                       return -1;
+               while (seg_start_page < n_pages) {
+                       ret = remap_segment(hugepages, seg_start_page,
+                                       cur_page, &mapped_seg_len);
+                       if (ret != 0)
+                               return -1;
+                       seg_start_page = seg_start_page + mapped_seg_len;
+                       mapped_seg_len = 0;
+               }
        }
        return 0;
  }

This works, but I feel like it's overcomplicated - the same logic you're trying to use can just be implemented using `find_biggest_free()` + `find_contig_free()` and returning `seg_len` from `remap_segment()`?

Something like the following:

---

diff --git a/lib/eal/linux/eal_memory.c b/lib/eal/linux/eal_memory.c
index 60fc8cc6ca..08acc787fc 100644
--- a/lib/eal/linux/eal_memory.c
+++ b/lib/eal/linux/eal_memory.c
@@ -681,6 +681,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)

        /* find free space in memseg lists */
        for (msl_idx = 0; msl_idx < RTE_MAX_MEMSEG_LISTS; msl_idx++) {
+               int free_len;
                bool empty;
                msl = &mcfg->memsegs[msl_idx];
                arr = &msl->memseg_arr;
@@ -692,18 +693,27 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)

                /* leave space for a hole if array is not empty */
                empty = arr->count == 0;
-               ms_idx = rte_fbarray_find_next_n_free(arr, 0,
-                               seg_len + (empty ? 0 : 1));

-               /* memseg list is full? */
-               if (ms_idx < 0)
-                       continue;
+               /* find start of the biggest contiguous block and its size */
+               ms_idx = rte_fbarray_find_biggest_free(arr, 0);
+               free_len = rte_fbarray_find_contig_free(arr, ms_idx);

                /* leave some space between memsegs, they are not IOVA
                 * contiguous, so they shouldn't be VA contiguous either.
                 */
-               if (!empty)
+               if (!empty) {
                        ms_idx++;
+                       free_len--;
+               }
+
+               /* memseg list is full? */
+               if (free_len < 1)
+                       continue;
+
+               /* we might not get all of the space we wanted */
+               free_len = RTE_MIN(seg_len, free_len);
+               seg_end = seg_start + free_len;
+               seg_len = seg_end - seg_start;
                break;
        }
        if (msl_idx == RTE_MAX_MEMSEG_LISTS) {
@@ -787,7 +797,7 @@ remap_segment(struct hugepage_file *hugepages, int seg_start, int seg_end)
        }
        RTE_LOG(DEBUG, EAL, "Allocated %" PRIu64 "M on socket %i\n",
                        (seg_len * page_sz) >> 20, socket_id);
-       return 0;
+       return seg_len;
 }

 static uint64_t
@@ -1022,10 +1032,17 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
                if (new_memseg) {
                        /* if this isn't the first time, remap segment */
                        if (cur_page != 0) {
-                               ret = remap_segment(hugepages, seg_start_page,
-                                               cur_page);
-                               if (ret != 0)
-                                       return -1;
+                               int n_remapped = 0;
+                               int n_needed = cur_page - seg_start_page;
+
+                               while (n_remapped < n_needed) {
+                                       ret = remap_segment(hugepages,
+                                                       seg_start_page,
+                                                       cur_page);
+                                       if (ret < 0)
+                                               return -1;
+                                       n_remapped += ret;
+                               }
                        }
                        /* remember where we started */
                        seg_start_page = cur_page;
@@ -1034,10 +1051,16 @@ remap_needed_hugepages(struct hugepage_file *hugepages, int n_pages)
        }
        /* we were stopped, but we didn't remap the last segment, do it now */
        if (cur_page != 0) {
-               ret = remap_segment(hugepages, seg_start_page,
-                               cur_page);
-               if (ret != 0)
-                       return -1;
+               int n_remapped = 0;
+               int n_needed = cur_page - seg_start_page;
+
+               while (n_remapped < n_needed) {
+                       ret = remap_segment(
+                                       hugepages, seg_start_page, cur_page);
+                       if (ret < 0)
+                               return -1;
+                       n_remapped += ret;
+               }
        }
        return 0;
 }

---

This should do the trick? Also, this probably needs to be duplicated for Windows and FreeBSD init as well, because AFAIK they follow the legacy mem init logic.

--
Thanks,
Anatoly

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