Kinetis Software Development Kit中的主题 How to speed up Ram Drive?

How to speed up Ram Drive?

sinterklaas — Thu, 03 Sep 2015 08:57:30 GMT

I created a ram drive using the function _io_mfs_install, and _io_register_file_system for the file system. I write to the disk using fwrite. All goes well without errors, but it is slow: around 45kB/s. Not what I expected of a ram drive. This is after compiler optimizations.

Any idea how to speed up the ram drive? What is the maximum it could theoretically reach?

Re: How to speed up Ram Drive?

xiangjun_rong — Tue, 08 Sep 2015 06:23:39 GMT

Hi, Sint,

Is it convenient to paste your code so that we can review your code even have a test? what is the software tools and hardware platform you are using?

XiangJun rong

Re: How to speed up Ram Drive?

sinterklaas — Fri, 11 Sep 2015 11:38:21 GMT

Software tools and hardware platform: I run with KDS3.0.0 and SDK library 1.1, and run this on a Freescale K64F.

I created the following simplified code snippet, with all error checking removed. First a ram disk is created, then a file is written to it. Writing goes very slow:

//Simplified version of creating ramdisk without error checking

const NIO_MEM_INIT_DATA_STRUCT NIO_MEM = { (uint32_t) myData, 8192};

_nio_dev_install(A_DEVICE, &nio_mem_dev_fn, (void *) &NIO_MEM) == NULL);

file_desc = open(A_DEVICE, 0);

io_mfs_install(file_desc, DISK, (_file_size) 0);

disk_file_desc = open(DISK, O_RDWR);

_io_register_file_system(disk_file_desc, DISK);

//write to a_file without error checking

a_file = fopen(a_file_name, "w");

fwrite(data_to_write, sizeof(char), size_of_data, a_file);

fclose(a_file)

Hope this code snippet helps.