FreeRTOS 10.1.1 HTTP server on SAM4E Xplained stops after sending one file

Kernel
22

That is an interesting solution, it also works for me. It is 3 percent faster than my solution with the extra mutex.

It looks like a silicon problem: as soon as the CPU fills all transmission descriptors , the peripheral “forgets” to call the transmit-complete-interrupt GMAC_ISR_TCOMP.

Solution:

When there are GMAC_TX_BUFFERS descriptors, we will make sure that there is always one descriptor free. That seems to do the trick.

The counting semaphore xTXDescriptorSemaphore will have a maximum count of GMAC_TX_BUFFERS-1.

While testing I saw that sometimes 2 TX descriptors were occupied, and both transmissions were completed with a GMAC_ISR_TCOMP interrupt.

I cleaned the sources and uploaded them to my branch IPv4_single_SAM_EMAC_race_condition.

Note that for the SAME70, we don’t have to calculate the checksum for transmission. Not calling vGMACGenerateChecksum() makes sending a lot faster.

Testing:

  • I tested both GMAC_TX_BUFFERS=2 and 6.
  • Also I varied the ipconfigNETWORK_MTU, between 586 and 1500.

Optimal settings for a IPERF3 TCP test:

#define GMAC_RX_BUFFERS                           4
#define GMAC_TX_BUFFERS                           6
#define ipconfigNETWORK_MTU                    1500
#define ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS   24
#define ipconfigIPERF_TX_BUFSIZE  ( 6 * ipconfigTCP_MSS )	/* Units of bytes. */
#define ipconfigIPERF_TX_WINSIZE  ( 4 )			/* Size in units of MSS */
#define ipconfigIPERF_RX_BUFSIZE  ( 6 * ipconfigTCP_MSS )	/* Units of bytes. */
#define ipconfigIPERF_RX_WINSIZE  ( 4 );			/* Size in units of MSS */

Would you be so kind to test the above driver from Github?
I will also keep my test with IPERF running here and transmit 1 TB :slight_smile:

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