summaryrefslogtreecommitdiff
path: root/net
diff options
context:
space:
mode:
authorShaohua Li <shli@fb.com>2015-06-11 16:50:48 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-07-10 10:37:56 -0700
commit00764c5282e8320c4938ed732d4d1df189880316 (patch)
treeda32b61e7d20ce7d5d89223cd1a050fa1372540f /net
parent1a3c14f438f91748cc2b2b51250e842a31920bfd (diff)
net: don't wait for order-3 page allocation
[ Upstream commit fb05e7a89f500cfc06ae277bdc911b281928995d ] We saw excessive direct memory compaction triggered by skb_page_frag_refill. This causes performance issues and add latency. Commit 5640f7685831e0 introduces the order-3 allocation. According to the changelog, the order-3 allocation isn't a must-have but to improve performance. But direct memory compaction has high overhead. The benefit of order-3 allocation can't compensate the overhead of direct 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, direct memory compaction will not be triggered, skb_page_frag_refill will fallback to order-0 immediately, hence the direct memory compaction overhead is avoided. In the allocation failure case, kswapd is waken up and doing compaction, so chances are allocation could success next time. alloc_skb_with_frags is the same. The mellanox driver does similar thing, if this is accepted, we must fix the driver too. V3: fix the same issue in alloc_skb_with_frags as pointed out by Eric V2: make the changelog clearer Cc: Eric Dumazet <edumazet@google.com> Cc: Chris Mason <clm@fb.com> Cc: Debabrata Banerjee <dbavatar@gmail.com> Signed-off-by: Shaohua Li <shli@fb.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/skbuff.c4
-rw-r--r--net/core/sock.c4
2 files changed, 6 insertions, 2 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 69ec61abfb37..8207f8d7f665 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -368,9 +368,11 @@ refill:
for (order = NETDEV_FRAG_PAGE_MAX_ORDER; ;) {
gfp_t gfp = gfp_mask;
- if (order)
+ if (order) {
gfp |= __GFP_COMP | __GFP_NOWARN |
__GFP_NOMEMALLOC;
+ gfp &= ~__GFP_WAIT;
+ }
nc->frag.page = alloc_pages(gfp, order);
if (likely(nc->frag.page))
break;
diff --git a/net/core/sock.c b/net/core/sock.c
index 650dd58ebd05..8ebfa52e5d70 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1914,8 +1914,10 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t prio)
do {
gfp_t gfp = prio;
- if (order)
+ if (order) {
gfp |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY;
+ gfp &= ~__GFP_WAIT;
+ }
pfrag->page = alloc_pages(gfp, order);
if (likely(pfrag->page)) {
pfrag->offset = 0;