Ethernet+sdcard transfer speed problem on stm32f407

[Amr Elsayed]

Posted on August 25, 2015 at 19:49

Hi I am building FTP server on

stm32f4DIS-BB + stm32f407-discovery

 I am using lwip ,and I am facing transfer speed issue.I get max upload speed about 165KB/s.this speed demonstrates two speeds (Ethernet + SD card writing speed)if I removed writing to sd card from code , i.e only receving data from Ethernet and dropping it then the speed reach 300KB/s which demonstrate only the ethernet data transfer speed, is that speed is normal ?how to improve it ? My Question is why my upload transfer is slow is that because of the sd card or the ethernet  ? I tried several ports for the sd card fafs driver , but same speed , previously the speed was only 125KB/s when I maximized sdclk to 48MHZ,this improve the speed to 165KB/s. For the ethernet, can I improve it's speed , I notice that my board receive 1460 byte at a time which is the size of the TCP_MSS, I don't know if I can modify it but I think it's a standard value , I tried to increase the size of the pbuf pool and the pbuf itself , but still same speed , and only i receive 1460 BYTE at a time. I am sharing the code of receiving data and writing it to the sd card :static err_t ftpd_datarecv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err){ struct ftpd_datastate *fsd = arg; if (err == ERR_OK && p != NULL) { struct pbuf *q; u16_t tot_len = 0; for (q = p; q != NULL; q = q->next) { int len; len = vfs_write(q->payload, 1, q->len, fsd->vfs_file); tot_len += len; if (len != q->len) break; } /* Inform TCP that we have taken the data. */ tcp_recved(pcb, tot_len); pbuf_free(p); } if (err == ERR_OK && p == NULL) { struct ftpd_msgstate *fsm; struct tcp_pcb *msgpcb; fsm = fsd->msgfs; msgpcb = fsd->msgpcb; vfs_close(fsd->vfs_file); fsd->vfs_file = NULL; ftpd_dataclose(pcb, fsd); fsm->datapcb = NULL; fsm->datafs = NULL; fsm->state = FTPD_IDLE; send_msg(msgpcb, fsm, msg226); } return ERR_OK;}can I do any modification on reception so that I can maximize the speed. Note that I get a higher download speed that reach 700KB/s which is wierd for me , why the upload is different than the download I will also share my clock settings as I tried to change them : &sharpdefine PLL_M      8&sharpdefine PLL_N      336/* SYSCLK = PLL_VCO / PLL_P */&sharpdefine PLL_P      2/* USB OTG FS, SDIO and RNG Clock =  PLL_VCO / PLLQ */&sharpdefine PLL_Q      7/* PLLI2S_VCO = (HSE_VALUE Or HSI_VALUE / PLL_M) * PLLI2S_N   I2SCLK = PLLI2S_VCO / PLLI2S_R */&sharpdefine PLLI2S_N   192&sharpdefine PLLI2S_R   5also for the sd card transfer speed :&sharpdefine SDIO_INIT_CLK_DIV                ((uint8_t)0x76)/**   * @brief  SDIO Data Transfer Frequency (25MHz max)   */&sharpdefine SDIO_TRANSFER_CLK_DIV            ((uint8_t)0x0) also part of my lwipopt.h /* MEMP_NUM_PBUF: the number of memp struct pbufs. If the application   sends a lot of data out of ROM (or other static memory), this   should be set high. */&sharpdefine MEMP_NUM_PBUF           60/* MEMP_NUM_UDP_PCB: the number of UDP protocol control blocks. One   per active UDP ''connection''. */&sharpdefine MEMP_NUM_UDP_PCB        1/* MEMP_NUM_TCP_PCB: the number of simulatenously active TCP   connections. */&sharpdefine MEMP_NUM_TCP_PCB        10/* MEMP_NUM_TCP_PCB_LISTEN: the number of listening TCP   connections. */&sharpdefine MEMP_NUM_TCP_PCB_LISTEN 6/* MEMP_NUM_TCP_SEG: the number of simultaneously queued TCP   segments. */&sharpdefine MEMP_NUM_TCP_SEG        12/* MEMP_NUM_SYS_TIMEOUT: the number of simulateously active   timeouts. */&sharpdefine MEMP_NUM_SYS_TIMEOUT    3/* ---------- Pbuf options ---------- *//* PBUF_POOL_SIZE: the number of buffers in the pbuf pool. */&sharpdefine PBUF_POOL_SIZE         10/* PBUF_POOL_BUFSIZE: the size of each pbuf in the pbuf pool. */&sharpdefine PBUF_POOL_BUFSIZE       512//&sharpdefine PBUF_POOL_BUFSIZE       1024/* ---------- TCP options ---------- */&sharpdefine LWIP_TCP                1&sharpdefine TCP_TTL                 255/* Controls if TCP should queue segments that arrive out of   order. Define to 0 if your device is low on memory. */&sharpdefine TCP_QUEUE_OOSEQ         0/* TCP Maximum segment size. */&sharpdefine TCP_MSS                 (1500 - 40)  /* TCP_MSS = (Ethernet MTU - IP header size - TCP header size) *//* TCP sender buffer space (bytes). */&sharpdefine TCP_SND_BUF             (4*TCP_MSS)/*  TCP_SND_QUEUELEN: TCP sender buffer space (pbufs). This must be at least  as much as (2 * TCP_SND_BUF/TCP_MSS) for things to work. */&sharpdefine TCP_SND_QUEUELEN        (2* TCP_SND_BUF/TCP_MSS)/* TCP receive window. */&sharpdefine TCP_WND                 (2*TCP_MSS)finally my stack and heap size :Stack_Size      EQU     0x00000400                AREA    STACK, NOINIT, READWRITE, ALIGN=3Stack_Mem       SPACE   Stack_Size__initial_sp; <h> Heap Configuration;   <o>  Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>; </h>Heap_Size       EQU     0x00015690                AREA    HEAP, NOINIT, READWRITE, ALIGN=3__heap_baseHeap_Mem        SPACE   Heap_Size__heap_limit #ethernet #sdcard #stm32f

[Tesla DeLorean]

Posted on August 25, 2015 at 21:36

It's not hard to benchmark SDIO speed independently. Writing is significantly slower then reading, because erasing/writing NAND is slow. The card hides a lot of the ugliness, but the underlying NAND probably has 128KB page sizes, and you need to consider this so your code uses it efficiently.

SDIO+FATFS is going to be slow if you use small unaligned blocks. Try to read/write at least 8KB. The sweet-spot is likely to be closer to 32KB. Consider using buffering schemes that get you to larger sizes.

[Amr Elsayed]

Posted on August 26, 2015 at 14:47Thank you Clive , It works , I copied the data from pbuf pools to a larger buffer 32kB and wrote it once to the SD card , Now I reach 1.6 MB/s. I think I wasted alot of memory , I was trying to expand pbuf buffers instead of copying data to another buffer but I Failed ,as they are small buffers connected on a chain and I can only take 1460 byte at a time from Ethernet then I have to free the pbuf buffer before taking more data,Do you have a solution ?