Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756527Ab3FSGcH (ORCPT ); Wed, 19 Jun 2013 02:32:07 -0400 Received: from mail-ee0-f42.google.com ([74.125.83.42]:47442 "EHLO mail-ee0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752041Ab3FSGcF (ORCPT ); Wed, 19 Jun 2013 02:32:05 -0400 Message-ID: <1371623518.3252.267.camel@edumazet-glaptop> Subject: Re: [net-next rfc 1/3] net: avoid high order memory allocation for queues by using flex array From: Eric Dumazet To: Jason Wang Cc: davem@davemloft.net, edumazet@google.com, hkchu@google.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 18 Jun 2013 23:31:58 -0700 In-Reply-To: <1371620452-49349-2-git-send-email-jasowang@redhat.com> References: <1371620452-49349-1-git-send-email-jasowang@redhat.com> <1371620452-49349-2-git-send-email-jasowang@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1963 Lines: 56 On Wed, 2013-06-19 at 13:40 +0800, Jason Wang wrote: > Currently, we use kcalloc to allocate rx/tx queues for a net device which could > be easily lead to a high order memory allocation request when initializing a > multiqueue net device. We can simply avoid this by switching to use flex array > which always allocate at order zero. > > Signed-off-by: Jason Wang > --- > include/linux/netdevice.h | 13 ++++++---- > net/core/dev.c | 57 ++++++++++++++++++++++++++++++++------------ > net/core/net-sysfs.c | 15 +++++++---- > 3 files changed, 58 insertions(+), 27 deletions(-) > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index 09b4188..c0b5d04 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -1230,7 +1231,7 @@ struct net_device { > > > #ifdef CONFIG_RPS > - struct netdev_rx_queue *_rx; > + struct flex_array *_rx; > > /* Number of RX queues allocated at register_netdev() time */ > unsigned int num_rx_queues; > @@ -1250,7 +1251,7 @@ struct net_device { > /* > * Cache lines mostly used on transmit path > */ > - struct netdev_queue *_tx ____cacheline_aligned_in_smp; > + struct flex_array *_tx ____cacheline_aligned_in_smp; > Using flex_array and adding overhead in this super critical part of network stack, only to avoid order-1 allocations done in GFP_KERNEL context is simply insane. We can revisit this in 2050 if we ever need order-4 allocations or so, and still use 4K pages. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/