Messages in this thread | | | Subject | Re: [net-next rfc 1/3] net: avoid high order memory allocation for queues by using flex array | From | Eric Dumazet <> | Date | Tue, 18 Jun 2013 23:31:58 -0700 |
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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 <jasowang@redhat.com> > --- > 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 <linux/atomic.h> > #include <asm/cache.h> > #include <asm/byteorder.h> > +#include <linux/flex_array.h> > > #include <linux/percpu.h> > #include <linux/rculist.h> > @@ -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.
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