From: Shaohua Li <shli@xxxxxx> Date: Thu, 11 Jun 2015 16:50:48 -0700 > 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@xxxxxxxxxx> > Cc: Chris Mason <clm@xxxxxx> > Cc: Debabrata Banerjee <dbavatar@xxxxxxxxx> > Signed-off-by: Shaohua Li <shli@xxxxxx> Applied and queued up for -stable, thanks! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>