From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [patch 05/13] remove last_rx update from loopback device Date: Tue, 15 Mar 2005 17:41:39 -0500 Message-ID: <423764A3.8030201@pobox.com> References: <200503152222.j2FMMbhG016805@shell0.pdx.osdl.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@oss.sgi.com, christoph@graphe.net, nirajk@calsoftinc.com, christoph@lameter.com, Shai@Scalex86.org To: akpm@osdl.org In-Reply-To: <200503152222.j2FMMbhG016805@shell0.pdx.osdl.net> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org akpm@osdl.org wrote: > From: Christoph Lameter > > The last_rx field in the loopback driver is updated on every xmit but is > not used otherwise. Accesses to ->last_rx cause unecessary traffic on the > interlink for NUMA systems which limits the performance of the loopback > device. > > The comment given at include/linux/netdevice.h says that last_rx may be > used for future network-power-down code, which is likely not relevant for > the loopback device (please let me know if it is otherwise ..). > > Signed-off-by: Niraj Kumar > Signed-off-by: Christoph Lameter > Signed-off-by: Shai Fultheim > Signed-off-by: Andrew Morton > --- > > 25-akpm/drivers/net/loopback.c | 2 -- > 1 files changed, 2 deletions(-) > > diff -puN drivers/net/loopback.c~remove-last_rx-update-from-loopback-device drivers/net/loopback.c > --- 25/drivers/net/loopback.c~remove-last_rx-update-from-loopback-device Tue Mar 15 14:19:53 2005 > +++ 25-akpm/drivers/net/loopback.c Tue Mar 15 14:19:53 2005 > @@ -144,8 +144,6 @@ static int loopback_xmit(struct sk_buff > return 0; > } > > - dev->last_rx = jiffies; > - > lb_stats = &per_cpu(loopback_stats, get_cpu()); > lb_stats->rx_bytes += skb->len; > lb_stats->tx_bytes += skb->len; I disagree. loopback.c is doing precisely what it should be doing. Jeff