Hi Nitin,
I believe your observation is correct. Adding Neale in case we missed
something.
Regards,
Florin
> On Jan 3, 2020, at 10:32 AM, Nitin Saxena <nsax...@marvell.com> wrote:
>
> Hi Dave,
>
> Thanks.
>
> I agree with your point that there is less chance of consecutive packets
> having same source IP. However both functions: ip4_local_check_src(),
> ip4_local_check_src_x2() already have the trick to avoid fib lookup for
> consecutive packets having same source IP. Correct me if I am wrong,
> currently else {} part in both aforementioned functions seems to be a dead
> code as PREDICT_FALSE(last_check->first) is always TRUE (as last_check->first
> is always 1 throughout ip4_local_inline() function).
>
> Also with my patch, there is no impact on cycle count of ip4_local node (both
> x86 and ARM) where source IP increments for every packet in a terminating
> frame. It does decrease cycles for ip4-local when all packets have similar
> source IP.
>
> So is there any gap in my understanding or is it deliberate to make else {}
> case as dead code?
>
> Thanks,
> Nitin
>
> From: Dave Barach (dbarach) <dbar...@cisco.com <mailto:dbar...@cisco.com>>
> Sent: Friday, January 3, 2020 8:08 PM
> To: Nitin Saxena <nsax...@marvell.com <mailto:nsax...@marvell.com>>;
> vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io>
> Subject: [EXT] RE: [vpp-dev] Check in ip4_local_inline()
>
> External Email
> Ask yourself how often there will be precisely one source (or dst) IP address
> in this path. Optimizing a specific lab/benchmark case may or may not make
> sense.
>
> D.
>
> From: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io> <vpp-dev@lists.fd.io
> <mailto:vpp-dev@lists.fd.io>> On Behalf Of Nitin Saxena
> Sent: Friday, January 3, 2020 8:02 AM
> To: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io>
> Subject: [vpp-dev] Check in ip4_local_inline()
>
> Hi,
>
> I am sending UDP termination packets to VPP interface with single source IP.
> I find that fib lookup is happening for every packet, even if source IP for
> current packet is same as last packet. Is it expected behavior? Following
> patch seems to avoid lookup for every packet.
>
> Thanks,
> Nitin
>
> diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
> index aa554ea..59edaba 100644
> --- a/src/vnet/ip/ip4_forward.c
> +++ b/src/vnet/ip/ip4_forward.c
> @@ -1542,6 +1542,7 @@ ip4_local_check_src (vlib_buffer_t * b, ip4_header_t *
> ip0,
> last_check->src.as_u32 = ip0->src_address.as_u32;
> last_check->lbi = lbi0;
> last_check->error = *error0;
> + last_check->first = 0;
> }
> else
> {
> @@ -1549,7 +1550,6 @@ ip4_local_check_src (vlib_buffer_t * b, ip4_header_t *
> ip0,
> vnet_buffer (b)->ip.adj_index[VLIB_TX];
> vnet_buffer (b)->ip.adj_index[VLIB_TX] = last_check->lbi;
> *error0 = last_check->error;
> - last_check->first = 0;
> }
> }
>
> @@ -1638,6 +1638,7 @@ ip4_local_check_src_x2 (vlib_buffer_t ** b,
> ip4_header_t ** ip,
> last_check->src.as_u32 = ip[1]->src_address.as_u32;
> last_check->lbi = lbi[1];
> last_check->error = error[1];
> + last_check->first = 0;
> }
> else
> {
> @@ -1651,7 +1652,6 @@ ip4_local_check_src_x2 (vlib_buffer_t ** b,
> ip4_header_t ** ip,
>
> error[0] = last_check->error;
> error[1] = last_check->error;
> - last_check->first = 0;
> }
> }
>
>
>
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