On Mon, Jun 20, 2011 at 11:52:20AM +0200, Kevin Wolf wrote: > Am 20.06.2011 11:40, schrieb Wen Congyang: > > At 06/20/2011 05:10 PM, Kevin Wolf Write: > >> Am 17.06.2011 03:33, schrieb Wen Congyang: > >>> If !s->clock_enabled or !rtl8139_receiver_enabled(s), it means that > >>> the nic will drop all packets from host. So qemu will keep getting > >>> packets from host and wasting CPU on dropping packets. This seems > >>> worse than packets that should be dropped but aren't. > >>> > >>> Signed-off-by: Wen Congyang <we...@cn.fujitsu.com> > >> > >> Which bug does this change fix? I'm still not convinced that we should > >> do it. > > > > Maybe not a bug fix now. As Michael S. Tsirkin said, if > > rtl8139_can_receive() > > returns 1, qemu will keep getting packets from host and wasting CPU on > > dropping packets. We can save CPU by return 0. > > Don't we waste memory instead then because we leave the packets queued > indefinitely? > > Kevin
Yes but the amount of wasted memory is bound from above so this doesn't seem too bad to me ... -- MST
