On 09/12/2017 08:37 PM, ychen wrote:
in function nla_alloc_flow_actions(), there is a check if action length is greater than MAX_ACTIONS_BUFSIZE(32k), then kernel datapath flow will not be installed, and packets will droppped. but in function xlate_actions(), there is such clause: if (nl_attr_oversized(ctx.odp_actions->size)) { /* These datapath actions are too big for a Netlink attribute, so we * can't hand them to the kernel directly. dpif_execute() can execute * them one by one with help, so just mark the result as SLOW_ACTION to * prevent the flow from being installed. */ COVERAGE_INC(xlate_actions_oversize); ctx.xout->slow |= SLOW_ACTION; } and in function nl_attr_oversized(), the clause is like this: return payload_size > UINT16_MAX - NLA_HDRLEN;so we can see that in user space, max action length is almost 64K, but in kernel space, max action length is only 32K. my question is: why the max action length is different? packet will drop when its action length exceeds 32K, but packet can excute in slow path when its action length exceeds 64K?
It's a kernel limitation. http://www.spinics.net/lists/netdev/msg431592.html - Greg
_______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
_______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
