dma传输与memcpy传输对比测试程序

最新推荐文章于 2025-04-27 10:59:50 发布

legendmaker

最新推荐文章于 2025-04-27 10:59:50 发布

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本文介绍了一个使用Linux DMA引擎进行大规模数据传输的测试模块，详细阐述了内存分配、通道请求及数据异步复制过程。

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/*
* DMA test module
*
* Copyright (C) 2007 KEDACOM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/init.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/async_tx.h>
#include <linux/jiffies.h>

#define XFER_TIMES 4000
#define XFER_LEN 1<<20

void *dma_src,*dma_dest;
struct dma_chan *chan = NULL;

static int __init dmatest_init(void)
{

   int xfer_order = get_order(XFER_LEN);
   int i,ret ;
   dma_cap_mask_t mask;
   dma_cookie_t cookie;
   enum dma_status status;
   u64 j1,j2;

   dma_src = __get_free_pages(GFP_KERNEL | GFP_DMA, xfer_order);
   if (!dma_src) {
       printk(KERN_ALERT "dma_src :alloc memory fail.\n");
       ret = -ENOMEM;
       goto CLEAN;

   }

   dma_dest = __get_free_pages(GFP_KERNEL | GFP_DMA, xfer_order);
   if (!dma_dest) {
       printk(KERN_ALERT "dma_dest :alloc memory fail.\n");
       ret = -ENOMEM;
       goto CLEAN;
   }
   printk(KERN_NOTICE"dma_src=%#x,dma_dest=%#x\n",dma_src,dma_dest);
   dma_cap_zero(mask);
   dma_cap_set(DMA_MEMCPY, mask);
   chan = dma_request_channel(mask, NULL, NULL);

   if (chan) {
       printk(KERN_NOTICE "dma_request_channel ok,current channel is : %s\n",dma_chan_name(chan));
   }else {
       printk(KERN_NOTICE "dma_request_channel fail,no dma channel available.\n");
       ret = -1;
       goto CLEAN;
   }

   j1 = get_jiffies_64();
   for(i =0;i<XFER_TIMES;i++) {
       cookie = dma_async_memcpy_buf_to_buf(chan, dma_dest, dma_src, XFER_LEN);
       if (dma_submit_error(cookie)) {
           printk(KERN_NOTICE"submit error\n");
           ret = -1;
           goto CLEAN;
       }
   }

   dma_async_memcpy_issue_pending(chan);
   do {
       status = dma_async_memcpy_complete(chan, cookie, NULL, NULL);

   } while (status == DMA_IN_PROGRESS);

   if (status != DMA_SUCCESS)
       printk(KERN_NOTICE "dma xfer dont accomplish,status=%d\n",status);
   j2 = get_jiffies_64();
   printk(KERN_NOTICE"dma xfer time cost:%d ms.\n",jiffies_to_msecs(j2-j1));

   j1 = get_jiffies_64();
   for(i =0;i<XFER_TIMES;i++){
       memcpy(dma_dest, dma_src, XFER_LEN);
   }
   j2 = get_jiffies_64();
   printk(KERN_NOTICE"memcpy time cost:%d ms.\n",jiffies_to_msecs(j2-j1));
   return 0;

CLEAN:
   if (chan)
       dma_release_channel(chan);

   if (dma_src)
       free_pages(dma_src,xfer_order);

   if (dma_dest)
       free_pages(dma_dest,xfer_order);

   return ret;

}
/* when compiled-in wait for drivers to load first */
module_init(dmatest_init);

static void __exit dmatest_exit(void)
{
   if (chan)
       dma_release_channel(chan);

   if (dma_src)
       free_pages(dma_src,get_order(XFER_LEN));

   if (dma_dest)
       free_pages(dma_dest,get_order(XFER_LEN));

}
module_exit(dmatest_exit);

MODULE_AUTHOR("ZhangZhuan <zhangzhuan@kedacom.com>");
MODULE_LICENSE("GPL v2");