Memset will cause the data flow block

Hi all,
    We have customized a DM8148(8127) board.
    I have get my sensor(1600x1200 YUV422 16bit) work yet.
    My application use case is based on IPNC_RDK_3.0 multich_tristream_lowPower.
    
    My application is work ok now.
    But if I do memset on a big memory area(for example 1 Mega bytes) in any other
    thread on COTEX-A8, the data flow will block, and the application will not exit when press ctrl+c.
    
    my test applicatin is like that:
    
    static char tmpbuf[1024*1024];
    
    int main()
    {
        /** init routine */
        /** start routine */
        
        while(gUI_mcfw_config.demoCfg.exitDemo == FALSE) {
            memset(tmpbuf, 0, sizeof(tmpbuf));
            printf("memset\n");
            sleep(1);
        }        
        
        /** stop routine */
        /** exit routine */
    }
    
    attatchment is the log with SYSTEM_DEBUG_RT.
    it seems that the link host IPC_BITS_IN never recei8623.session.logve the buffer.

    Could someone tell me why?
    Please help!