topic RTCS send() with OPT_SEND_NOWAIT takes a while to return in MQX Software Solutions

RTCS send() with OPT_SEND_NOWAIT takes a while to return

rajbatra — Thu, 31 Mar 2016 22:56:43 GMT

I timed sending 1450 bytes via socket send (it's a TCP Stream), on my K64, it can take up to 800 uS. I tried with OPT_SEND_NOWAIT, not using the push flag, and even directly setting the MSG_DONTWAIT in the send command and still see 800uS.

The timing was done on a scope (setting pin high/low before/after command).

I noticed that sock_stream.c, SOCK_STREAM_send calls RTCSCMD_issue which calls RTCS_msg_send_blocked in both the WAIT and NOWAIT state. There is an RTCS_msg_send command that isn't called. Not sure if this is why it's taking so long to return or is this normal?

Thanks,

-Raj

Re: RTCS send() with OPT_SEND_NOWAIT takes a while to return

soledad — Thu, 07 Apr 2016 00:09:41 GMT

Hello,

Which MQX version are you using?

There exists 200 ms TCP ACK Delay in Windows 7 tcpip stack. It is intentional by Microsoft, it can be switched off. The workaround is here:

http://social.technet.microsoft.com/Forums/en-US/w7itpronetworking/thread/9f476410-a7a6-4f5d-b9a9-0a63a2bab121/

Please let me know if this helps,

Have a great day,
Sol

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Re: RTCS send() with OPT_SEND_NOWAIT takes a while to return

rajbatra — Thu, 07 Apr 2016 16:20:13 GMT

Hi Sol,

I'm using mqx that came with KSDK 1.2.

I'm using Mac OSX. Send call takes 810uS (much less than 200ms), but higher than I expect for a No Wait operation. For me to prepare the buffer to send only takes 10uS.

Thanks,

-Raj