Hello! BTW, check this a few lines above:
gfp_head = gfp_mask; if (gfp_head & __GFP_WAIT) gfp_head |= __GFP_REPEAT; What is this?? On Tue, Feb 13, 2018 at 5:21 PM, Andrey Ryabinin <aryabi...@virtuozzo.com> wrote: > From: Shaohua Li <s...@fb.com> > > 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 <eduma...@google.com> > Cc: Chris Mason <c...@fb.com> > Cc: Debabrata Banerjee <dbava...@gmail.com> > Signed-off-by: Shaohua Li <s...@fb.com> > Acked-by: Eric Dumazet <eduma...@google.com> > Signed-off-by: David S. Miller <da...@davemloft.net> > > https://jira.sw.ru/browse/PSBM-81488 > (cherry picked from commit fb05e7a89f500cfc06ae277bdc911b281928995d) > Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> > --- > net/core/skbuff.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 4147d7219589..dca9d1d9676b 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -4360,7 +4360,7 @@ struct sk_buff *alloc_skb_with_frags(unsigned long > header_len, > > while (order) { > if (npages >= 1 << order) { > - page = alloc_pages(gfp_mask | > + page = alloc_pages((gfp_mask & ~__GFP_WAIT) | > __GFP_COMP | > __GFP_NOWARN | > __GFP_NORETRY, > -- > 2.13.6 > _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel