On 3/12/25 11:02, Chao Yu wrote:
> 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.
Anyway, code looks clean, I think we can take a look at this later.
Reviewed-by: Chao Yu <c...@kernel.org>
Thanks,
>
> 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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