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>
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]
> *Sent:* Friday, July 7, 2017 8:04 PM
> *To:* Dave Barach (dbarach) <dbar...@cisco.com>
> *Cc:* 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>
> 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] *On
> Behalf Of *Yuliang Li
> *Sent:* Friday, July 7, 2017 1:14 PM
> *To:* 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
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