We saw excessive memory compaction triggered by skb_page_frag_refill.
This causes performance issues. Commit 5640f7685831e0 introduces the
order-3 allocation to improve performance. But memory compaction has
high overhead. The benefit of order-3 allocation can't compensate the
overhead of memory compaction.
This patch makes the order-3 page allocation atomic. If there is no
memory pressure and memory isn't fragmented, the alloction will still
success, so we don't sacrifice the order-3 benefit here. If the atomic
allocation fails, compaction will not be triggered and we will fallback
to order-0 immediately.
The mellanox driver does similar thing, if this is accepted, we must fix
the driver too.
Cc: Eric Dumazet <eduma...@google.com>
Signed-off-by: Shaohua Li <s...@fb.com>
---
net/core/sock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/sock.c b/net/core/sock.c
index 292f422..e9855a4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1883,7 +1883,7 @@ bool skb_page_frag_refill(unsigned int sz, struct
page_frag *pfrag, gfp_t gfp)
pfrag->offset = 0;
if (SKB_FRAG_PAGE_ORDER) {
- pfrag->page = alloc_pages(gfp | __GFP_COMP |
+ pfrag->page = alloc_pages((gfp & ~__GFP_WAIT) | __GFP_COMP |
__GFP_NOWARN | __GFP_NORETRY,
SKB_FRAG_PAGE_ORDER);
if (likely(pfrag->page)) {
--
1.8.1
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