Why are buffers usefulness? I thought it is useful to cache table-missed packets and transfer the packets after controller's decision. Without it, the controller has to receive all bytes of the packets and re-inject them afterwards. Or else the connections may be broken for loss of packets.
2017-03-17 11:54 GMT+08:00 Ben Pfaff <b...@ovn.org>: > You can change anything in OVS by modifying the source code, so this > isn't really a surprise. > > Buffers aren't very useful, so we've never made them adjustable, and OVS > 2.7 removes them entirely. > > On Fri, Mar 17, 2017 at 10:21:49AM +0800, Big Strong wrote: > > From the source code I found the way to modify n_buffers by adjusting the > > PKTBUF_BITS. For example, I can set it to 1024 by setting PKTBUF_BITS to > > 10. > > Does the modification have any some side-effects? Why doesn't OVS make it > > adjustable? > > > > /* Buffers are identified by a 32-bit opaque ID. We divide the ID > > > * into a buffer number (low bits) and a cookie (high bits). The > buffer > > > number > > > * is an index into an array of buffers. The cookie distinguishes > between > > > * different packets that have occupied a single buffer. Thus, the > more > > > * buffers we have, the lower-quality the cookie... */ > > > #define PKTBUF_BITS 8 > > > #define PKTBUF_MASK (PKTBUF_CNT - 1) > > > #define PKTBUF_CNT (1u << PKTBUF_BITS) > > > #define COOKIE_BITS (32 - PKTBUF_BITS) > > > #define COOKIE_MAX ((1u << COOKIE_BITS) - 1) > > > > > > 2017-03-16 23:07 GMT+08:00 Ben Pfaff <b...@ovn.org>: > > > > > OVS sends a packet to the controller if the flow table tells it to do > > > so. There's nothing in OpenFlow that restricts this on the basis of a > > > flow or a response from the controller. > > > > > > n_buffers is not adjustable. > > > > > > On Thu, Mar 16, 2017 at 10:22:38PM +0800, Big Strong wrote: > > > > @Ben, does it mean ovs would repeatedly send packet in messages as > long > > > as > > > > no response is got from controller? What will happen when a same > packet > > > > comes to ovs while the old packet in message is still not handled? > > > > > > > > Another question, is the n_buffers size adjustable using > > > > ovs-ofctl/ovs-vsctl command? I want a larger n_buffers rather than > the > > > > default 256. > > > > > > > > Regards. > > > > > > > > 2017-03-16 4:54 GMT+08:00 Ben Pfaff <b...@ovn.org>: > > > > > > > > > On Wed, Mar 15, 2017 at 01:34:56PM +0800, yiyefuping198425 wrote: > > > > > > I'm asking for assistance to fix this issue: ovs send many > packets > > > of a > > > > > table miss flow instead of the first packet. > > > > > > > > > > That's how OpenFlow works. > > > > > _______________________________________________ > > > > > discuss mailing list > > > > > disc...@openvswitch.org > > > > > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss > > > > > > > > >
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