From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [net-next rfc 1/3] net: avoid high order memory allocation for queues by using flex array Date: Wed, 19 Jun 2013 15:14:52 +0800 Message-ID: <51C15A6C.1090702@redhat.com> References: <1371620452-49349-1-git-send-email-jasowang@redhat.com> <1371620452-49349-2-git-send-email-jasowang@redhat.com> <1371623518.3252.267.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, edumazet@google.com, hkchu@google.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Eric Dumazet Return-path: In-Reply-To: <1371623518.3252.267.camel@edumazet-glaptop> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 06/19/2013 02:31 PM, Eric Dumazet wrote: > 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. Yes, and I also miss the fact of GFP_KERNEL allocation. > We can revisit this in 2050 if we ever need order-4 allocations or so, > and still use 4K pages. > > Will drop this patch, thanks.