On 3/12/25 03:36, Jaegeuk Kim wrote:
> On 03/11, Chao Yu wrote:
>> On 3/4/25 09:10, Jaegeuk Kim via Linux-f2fs-devel wrote:
>>> From: Jaegeuk Kim <jaeg...@google.com>
>>>
>>> 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 <jaeg...@google.com>
>>> ---
>>> tools/f2fs_io/f2fs_io.c | 110 ++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 110 insertions(+)
>>>
>>> diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
>>> index b72c26648f56..8431262575e0 100644
>>> --- a/tools/f2fs_io/f2fs_io.c
>>> +++ b/tools/f2fs_io/f2fs_io.c
>>> @@ -1018,6 +1018,115 @@ 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;
>>
>> Do we need to call mlock to hold allocated cache in the memory, if
>> administrator enables swap, memory fragment will be gone once anonymous
>> pages are swapped to device?
>
> Hmm, the test is going to use this very intensively, so is it possible?
Not sure, but I doubt it is possible to happen in low-end device? due to it has
very less memory and system may has already token the most of memory.
Thanks,
>
>>
>> Thanks,
>>
>>> +
>>> + /* 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");
>>> +
>>> + 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" \
>>> @@ -2002,6 +2111,7 @@ const struct cmd_desc cmd_list[] = {
>>> CMD(write_advice),
>>> CMD(read),
>>> CMD(randread),
>>> + CMD(fragread),
>>> CMD(fiemap),
>>> CMD(gc_urgent),
>>> CMD(defrag_file),
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