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__napi_schedule might raise softirq but nothing causes do_softirq to trigger, so it does not in fact run. As a result, the error message "NOHZ: local_softirq_pending 08" sometimes occurs during boot of a KVM guest when the network service is started and we are oom: ... Bringing up loopback interface: [ OK ] Bringing up interface eth0: Determining IP information for eth0...NOHZ: local_softirq_pending 08 done. [ OK ] ... Further, receive queue processing might get delayed indefinitely until some interrupt triggers: virtio_net expected napi to be run immediately. One way to cause do_softirq to be executed is by invoking local_bh_enable(). As __napi_schedule is normally called from bh or irq context, this seems to make sense: disable bh before __napi_schedule and enable afterwards. In fact it's a very complicated way of calling do_softirq(), and works since this function is only used when we are not in interrupt context. It's not hot at all, in any ideal scenario. Reported-by: Ulrich Obergfell <uobergfe@redhat.com> Tested-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> |
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|---|---|---|
| .. | ||
| appletalk | ||
| arcnet | ||
| bonding | ||
| caif | ||
| can | ||
| cris | ||
| dsa | ||
| ethernet | ||
| fddi | ||
| hamradio | ||
| hippi | ||
| hyperv | ||
| irda | ||
| phy | ||
| plip | ||
| ppp | ||
| slip | ||
| team | ||
| tokenring | ||
| usb | ||
| vmxnet3 | ||
| wan | ||
| wimax | ||
| wireless | ||
| xen-netback | ||
| dummy.c | ||
| eql.c | ||
| ifb.c | ||
| Kconfig | ||
| LICENSE.SRC | ||
| loopback.c | ||
| macvlan.c | ||
| macvtap.c | ||
| Makefile | ||
| mdio.c | ||
| mii.c | ||
| netconsole.c | ||
| rionet.c | ||
| sb1000.c | ||
| Space.c | ||
| sungem_phy.c | ||
| tun.c | ||
| veth.c | ||
| virtio_net.c | ||
| xen-netfront.c | ||