On 2024/8/27 1:00, Alexander Duyck wrote:

quoted

On Mon, Aug 26, 2024 at 5:46 AM Yunsheng Lin [off-list ref] wrote:

quoted

It seems there is about 24Bytes binary size increase for
__page_frag_cache_refill() after refactoring in arm64 system
with 64K PAGE_SIZE. By doing the gdb disassembling, It seems
we can have more than 100Bytes decrease for the binary size
by using __alloc_pages() to replace alloc_pages_node(), as
there seems to be some unnecessary checking for nid being
NUMA_NO_NODE, especially when page_frag is part of the mm
system.

CC: Alexander Duyck <redacted>
Signed-off-by: Yunsheng Lin <redacted>
---
 mm/page_frag_cache.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c
index bba59c87d478..e0ad3de11249 100644
--- a/mm/page_frag_cache.c
+++ b/mm/page_frag_cache.c

@@ -28,11 +28,11 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
        gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) |  __GFP_COMP |
                   __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC;
-       page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
-                               PAGE_FRAG_CACHE_MAX_ORDER);
+       page = __alloc_pages(gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER,
+                            numa_mem_id(), NULL);
 #endif
        if (unlikely(!page)) {
-               page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
+               page = __alloc_pages(gfp, 0, numa_mem_id(), NULL);
                if (unlikely(!page)) {
                        nc->encoded_page = 0;
                        return NULL;

I still think this would be better served by fixing alloc_pages_node
to drop the superfluous checks rather than changing the function. We
would get more gain by just addressing the builtin constant and
NUMA_NO_NODE case there.

I am supposing by 'just addressing the builtin constant and NUMA_NO_NODE
case', it meant the below change from the previous discussion:

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 01a49be7c98d..009ffb50d8cd 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h

@@ -290,6 +290,9 @@ struct folio *__folio_alloc_node_noprof(gfp_t gfp, unsigned int order, int nid)
 static inline struct page *alloc_pages_node_noprof(int nid, gfp_t gfp_mask,
                                                   unsigned int order)
 {
+       if (__builtin_constant_p(nid) && nid == NUMA_NO_NODE)
+               return __alloc_pages_noprof(gfp_mask, order, numa_mem_id(), NULL);
+
        if (nid == NUMA_NO_NODE)
                nid = numa_mem_id();

Actually it does not seem to get more gain by judging from binary size
changing as below, vmlinux.org is the image after this patchset, and
vmlinux is the image after this patchset with this patch reverted and
with above change applied.

[linyunsheng@localhost net-next]$ ./scripts/bloat-o-meter vmlinux.org vmlinux
add/remove: 0/2 grow/shrink: 16/12 up/down: 432/-340 (92)
Function                                     old     new   delta
new_slab                                     808    1124    +316
its_probe_one                               2860    2908     +48