www w×××Sent from my Verizon, Samsung Galaxy smartphone -------- Original message -------- From: Florin Coras <fcoras.li...@gmail.com> Date: 7/8/17 6:41 AM (GMT+05:30) To: Yuliang Li <yuliang...@yale.edu> Cc: vpp-dev@lists.fd.io Subject: Re: [vpp-dev] set mapping from node to thread 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 aaa!a@@a@@@@aaa××aaa <yuliang...@yale.edu<mailto: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
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