Re: [f2fs-dev] [f2fs-dev v2] [PATCH] f2fs_io: add fragread command to evaluate fragmented buffer for reads

[Jaegeuk Kim via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

Ping.

On 03/17, Jaegeuk Kim via Linux-f2fs-devel wrote:
> This adds a fragread command in f2fs_io, which is able to measure the
> read performance on fragmented data buffer.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
> ---
> 
>  Change log from v1:
>   - add mlock
> 
>  tools/f2fs_io/f2fs_io.c | 114 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 114 insertions(+)
> 
> diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
> index 44d389dbd771..57a931d5769c 100644
> --- a/tools/f2fs_io/f2fs_io.c
> +++ b/tools/f2fs_io/f2fs_io.c
> @@ -1005,6 +1005,119 @@ static void do_read(int argc, char **argv, const struct cmd_desc *cmd)
>  	exit(0);
>  }
>  
> +#define fragread_desc "read data with a fragmented buffer from file"
> +#define fragread_help					\
> +"f2fs_io fragread [chunk_size in 4kb] [offset in chunk_size] [count] [advice] [file_path]\n\n"	\
> +"Read data in file_path and print nbytes\n"		\
> +"advice can be\n"					\
> +" 1 : set sequential|willneed\n"			\
> +" 0 : none\n"						\
> +
> +#ifndef PAGE_SIZE
> +#define PAGE_SIZE sysconf(_SC_PAGESIZE)
> +#endif
> +#define ALLOC_SIZE (2 * 1024 * 1024 - 4 * 1024) // 2MB - 4KB
> +
> +static void do_fragread(int argc, char **argv, const struct cmd_desc *cmd)
> +{
> +	u64 buf_size = 0, ret = 0, read_cnt = 0;
> +	u64 offset;
> +	char *buf = NULL;
> +	uintptr_t idx, ptr;
> +	unsigned bs, count, i;
> +	u64 total_time = 0;
> +	int flags = 0, alloc_count = 0;
> +	void *mem_hole, **mem_holes;
> +	int fd, advice;
> +
> +	if (argc != 6) {
> +		fputs("Excess arguments\n\n", stderr);
> +		fputs(cmd->cmd_help, stderr);
> +		exit(1);
> +	}
> +
> +	bs = atoi(argv[1]);
> +	if (bs > 256 * 1024)
> +		die("Too big chunk size - limit: 1GB");
> +	buf_size = bs * F2FS_DEFAULT_BLKSIZE;
> +
> +	offset = atoi(argv[2]) * buf_size;
> +	count = atoi(argv[3]);
> +	advice = atoi(argv[4]);
> +	mem_holes = xmalloc(sizeof(void *) * (buf_size / PAGE_SIZE));
> +
> +	/* 1. Allocate the buffer using mmap. */
> +	buf = mmap(NULL, buf_size, PROT_READ | PROT_WRITE,
> +				MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +
> +	/* 2. Loop and touch each page. */
> +	for (idx = (uintptr_t)buf; idx < (uintptr_t)buf + buf_size;
> +						idx += PAGE_SIZE)
> +	{
> +		/* Touch the current page. */
> +		volatile char *page = (volatile char *)idx;
> +		*page;
> +
> +		/* 3. Allocate (2M - 4K) memory using mmap and touch all of it. */
> +		mem_hole = mmap(NULL, ALLOC_SIZE, PROT_READ | PROT_WRITE,
> +					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> +		if (mem_hole == MAP_FAILED)
> +			die_errno("map failed");
> +
> +		/* Store the allocated memory pointer. */
> +		mem_holes[alloc_count++] = mem_hole;
> +
> +		/* Touch all allocated memory. */
> +		for (ptr = (uintptr_t)mem_hole;
> +			ptr < (uintptr_t)mem_hole + ALLOC_SIZE;
> +						ptr += PAGE_SIZE) {
> +			volatile char *alloc_page = (volatile char *)ptr;
> +			*alloc_page;
> +		}
> +	}
> +	printf("Touched allocated memory: count = %u\n", alloc_count);
> +	printf(" - allocated memory: = ");
> +	for (idx = 0; idx < 5; idx++)
> +		printf(" %p", mem_holes[idx]);
> +	printf("\n");
> +
> +	/* Pin the pages. */
> +	if (mlock(buf, buf_size))
> +		die_errno("mlock failed");
> +
> +	fd = xopen(argv[5], O_RDONLY | flags, 0);
> +
> +	if (advice) {
> +		if (posix_fadvise(fd, 0, F2FS_DEFAULT_BLKSIZE,
> +				POSIX_FADV_SEQUENTIAL) != 0)
> +			die_errno("fadvise failed");
> +		if (posix_fadvise(fd, 0, F2FS_DEFAULT_BLKSIZE,
> +				POSIX_FADV_WILLNEED) != 0)
> +			die_errno("fadvise failed");
> +		printf("fadvise SEQUENTIAL|WILLNEED to a file: %s\n", argv[5]);
> +	}
> +
> +	total_time = get_current_us();
> +
> +	for (i = 0; i < count; i++) {
> +		ret = pread(fd, buf, buf_size, offset + buf_size * i);
> +		if (ret != buf_size) {
> +			printf("pread expected: %"PRIu64", readed: %"PRIu64"\n",
> +					buf_size, ret);
> +			if (ret > 0)
> +				read_cnt += ret;
> +			break;
> +		}
> +
> +		read_cnt += ret;
> +	}
> +	printf("Fragmented_Read %"PRIu64" bytes total_time = %"PRIu64" us, BW = %.Lf MB/s\n",
> +		read_cnt, get_current_us() - total_time,
> +		((long double)read_cnt / (get_current_us() - total_time)));
> +	printf("\n");
> +	exit(0);
> +}
> +
>  #define randread_desc "random read data from file"
>  #define randread_help					\
>  "f2fs_io randread [chunk_size in 4kb] [count] [IO] [advise] [file_path]\n\n"	\
> @@ -1989,6 +2102,7 @@ const struct cmd_desc cmd_list[] = {
>  	CMD(write_advice),
>  	CMD(read),
>  	CMD(randread),
> +	CMD(fragread),
>  	CMD(fiemap),
>  	CMD(gc_urgent),
>  	CMD(defrag_file),
> -- 
> 2.49.0.rc1.451.g8f38331e32-goog
> 
> 
> 
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> Linux-f2fs-devel@lists.sourceforge.net
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