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Date: Thu, 4 Dec 2014 05:45:01 -0500 (EST) From: Pankaj Gupta <pagupta@...hat.com> To: "Michael S. Tsirkin" <mst@...hat.com> Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org, davem@...emloft.net, jasowang@...hat.com, dgibson@...hat.com, vfalico@...il.com, edumazet@...gle.com, vyasevic@...hat.com, hkchu@...gle.com, wuzhy@...ux.vnet.ibm.com, xemul@...allels.com, therbert@...gle.com, bhutchings@...arflare.com, xii@...gle.com, stephen@...workplumber.org, jiri@...nulli.us, sergei shtylyov <sergei.shtylyov@...entembedded.com> Subject: Re: [PATCH v3 net-next 1/2] net: allow large number of rx queues > > On Wed, Dec 03, 2014 at 12:49:36PM +0530, Pankaj Gupta wrote: > > netif_alloc_rx_queues() uses kcalloc() to allocate memory > > for "struct netdev_queue *_rx" array. > > If we are doing large rx queue allocation kcalloc() might > > fail, so this patch does a fallback to vzalloc(). > > Similar implementation is done for tx queue allocation in > > netif_alloc_netdev_queues(). > > > > We avoid failure of high order memory allocation > > with the help of vzalloc(), this allows us to do large > > rx and tx queue allocation which in turn helps us to > > increase the number of queues in tun. > > > > As vmalloc() adds overhead on a critical network path, > > __GFP_REPEAT flag is used with kzalloc() to do this fallback > > only when really needed. > > > > Signed-off-by: Pankaj Gupta <pagupta@...hat.com> > > Reviewed-by: Michael S. Tsirkin <mst@...hat.com> > > Reviewed-by: David Gibson <dgibson@...hat.com> > > --- > > net/core/dev.c | 19 +++++++++++++------ > > 1 file changed, 13 insertions(+), 6 deletions(-) > > > > diff --git a/net/core/dev.c b/net/core/dev.c > > index e916ba8..abe9560 100644 > > --- a/net/core/dev.c > > +++ b/net/core/dev.c > > @@ -6059,17 +6059,25 @@ void netif_stacked_transfer_operstate(const struct > > net_device *rootdev, > > EXPORT_SYMBOL(netif_stacked_transfer_operstate); > > > > #ifdef CONFIG_SYSFS > > +static void netif_free_rx_queues(struct net_device *dev) > > +{ > > + kvfree(dev->_rx); > > +} > > + > > I would just open-code this. I will make the changes with the next version. Thanks, Pankaj > > > static int netif_alloc_rx_queues(struct net_device *dev) > > { > > unsigned int i, count = dev->num_rx_queues; > > struct netdev_rx_queue *rx; > > + size_t sz = count * sizeof(*rx); > > > > BUG_ON(count < 1); > > > > - rx = kcalloc(count, sizeof(struct netdev_rx_queue), GFP_KERNEL); > > - if (!rx) > > - return -ENOMEM; > > - > > + rx = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT); > > + if (!rx) { > > + rx = vzalloc(sz); > > + if (!rx) > > + return -ENOMEM; > > + } > > dev->_rx = rx; > > > > for (i = 0; i < count; i++) > > @@ -6698,9 +6706,8 @@ void free_netdev(struct net_device *dev) > > > > netif_free_tx_queues(dev); > > #ifdef CONFIG_SYSFS > > - kfree(dev->_rx); > > + netif_free_rx_queues(dev); > > #endif > > - > > and I think it's nicer with the empty line. > > > kfree(rcu_dereference_protected(dev->ingress_queue, 1)); > > > > /* Flush device addresses */ > > -- > > 1.8.3.1 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe netdev" in > > the body of a message to majordomo@...r.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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