Hi Yuliang, Are you running with dpdk or with tap/af_packet interfaces? As far as I remember multithreading for the last two might not work properly.
Florin > On Jul 7, 2017, at 5:55 PM, Yuliang Li <yuliang...@yale.edu> wrote: > > I printed 3 thread_index, and all 3 shows the same value: > > 1. vlib_frame_t's thread_index: > For each pending frame p: > vlib_pending_frame_t *p = nm->pending_frames + i; > I get the vlib_frame_t f: > vlib_frame_t *f = vlib_get_frame (vm, p->frame_index); > and I print f->thread_index > > 2. vlib_node_runtime_t's thread_indes: > For each pending frame p, I get its node runtime nr: > vlib_node_runtime_t *nr = vec_elt_at_index > (nm->nodes_by_type[VLIB_NODE_TYPE_INTERNAL], p->node_runtime_index); > and I print nr->thread_index > > 3. vlib_main_t's thread_index: > I print vm->thread_index > > > On Fri, Jul 7, 2017 at 5:37 PM, Dave Barach (dbarach) <dbar...@cisco.com > <mailto:dbar...@cisco.com>> wrote: > What exactly were you printing? Vlib_pending_frame_t’s don’t have a > thread_index field...: <> > > > > > /* A frame pending dispatch by main loop. */ > > typedef struct > > { > > /* Node and runtime for this frame. */ > > u32 node_runtime_index; > > > > /* Frame index (in the heap). */ > > u32 frame_index; > > > > /* Start of next frames for this node. */ > > u32 next_frame_index; > > > > /* Special value for next_frame_index when there is no next frame. */ > > #define VLIB_PENDING_FRAME_NO_NEXT_FRAME ((u32) ~0) > > } vlib_pending_frame_t; > > > > Thanks… Dave > > > > From: Yuliang Li [mailto:yuliang...@yale.edu <mailto:yuliang...@yale.edu>] > Sent: Friday, July 7, 2017 8:04 PM > To: Dave Barach (dbarach) <dbar...@cisco.com <mailto:dbar...@cisco.com>> > Cc: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> > Subject: Re: [vpp-dev] set mapping from node to thread > > > > Hi Dave, > > > > Thanks for the detailed response. > > > > However, from the experiment I did, I see the same packet being processed by > two threads. That is why I asked this question. Maybe I made some mistakes, > here is what I did: > > > > - In vlib_main_or_worker_loop function, I print out all pending frames here, > as well as the thread_index of them, and the node name. > > - I start the vpp with 4 worker threads, and set up SNAT according to the > progressive tutorial <https://wiki.fd.io/view/VPP/Progressive_VPP_Tutorial>. > > - I run iperf that go through the SNAT. > > > > The printed information shows that, each TCP packet from the inside to the > outside of the SNAT will go through the ethernet-input and snat-in2out. But > the thread_index at the ethernet-input is 2, while the thread_index at > snat-in2out is 1. > > > > Is the above expected? > > > > Thanks, > > > > On Fri, Jul 7, 2017 at 12:22 PM, Dave Barach (dbarach) <dbar...@cisco.com > <mailto:dbar...@cisco.com>> wrote: > > Dear Yuliang, <> > > > From a high level: vpp creates N identical graph replicas in a multi-core > configuration. When practicable, we use hardware RSS hashing to ensure that > all packets belonging to a specific flow are processed [in order!] by the > same thread / graph replica. In effect, embarrassing parallelism. > > > > It’s easy enough to hand off packets between threads - see the “handoff-node” > - but we avoid that whenever possible. > > > > Although one could - and I have - divided graph nodes across threads to > create pipelines, that scheme needs significant dynamic tuning to handle a > traffic pattern change. It’s hard to map nodes onto cores so that each thread > in a pipeline uses approximately the same number of clocks/pkt; critical, > since pipelines run at the speed of the slowest stage. > > > > It’s possible to hand off a full frame of packets for less than two > clocks/pkt. Unfortunately, that’s the least significant issue. Handing off a > packet from one core/thread to another guarantees a bunch of memory/cache > subsystem pressure as the system moves packet data and metadata from A to B. > > > > HTH... Dave > > > > From: vpp-dev-boun...@lists.fd.io <mailto:vpp-dev-boun...@lists.fd.io> > [mailto:vpp-dev-boun...@lists.fd.io <mailto:vpp-dev-boun...@lists.fd.io>] On > Behalf Of Yuliang Li > Sent: Friday, July 7, 2017 1:14 PM > To: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> > Subject: [vpp-dev] set mapping from node to thread > > > > Hi, > > > > Is there a way to set which node should run on which thread? And is there a > command that shows the mapping from nodes to threads? > > > > Thanks, > > -- > > Yuliang Li > > PhD student > > Department of Computer Science > > Yale University > > > > > > > -- > > Yuliang Li > > PhD student > > Department of Computer Science > > Yale University > > > > > -- > Yuliang Li > PhD student > Department of Computer Science > Yale University > _______________________________________________ > vpp-dev mailing list > vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> > https://lists.fd.io/mailman/listinfo/vpp-dev > <https://lists.fd.io/mailman/listinfo/vpp-dev>
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