[f2fs-dev] [PATCH] f2fs-tools: f2fs_io: no memcpy for mmap read

[Jaegeuk Kim]

This replaces the mmmap read flow to get the maximum performance.

Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
---
 tools/f2fs_io/f2fs_io.c | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
index 73ac700f8209..51baded4cb4b 100644
--- a/tools/f2fs_io/f2fs_io.c
+++ b/tools/f2fs_io/f2fs_io.c
@@ -684,6 +684,7 @@ static void do_read(int argc, char **argv, const struct 
cmd_desc *cmd)
        char *data;
        char *print_buf = NULL;
        unsigned bs, count, i, print_bytes;
+       u64 total_time = 0;
        int flags = 0;
        int do_mmap = 0;
        int fd;
@@ -719,28 +720,29 @@ static void do_read(int argc, char **argv, const struct 
cmd_desc *cmd)
 
        fd = xopen(argv[6], O_RDONLY | flags, 0);
 
+       total_time = get_current_us();
        if (do_mmap) {
                data = mmap(NULL, count * buf_size, PROT_READ,
-                                               MAP_SHARED, fd, offset);
+                                               MAP_SHARED | MAP_POPULATE, fd, 
offset);
                if (data == MAP_FAILED)
                        die("Mmap failed");
        }
-
-       for (i = 0; i < count; i++) {
-               if (do_mmap) {
-                       memcpy(buf, data + offset + buf_size * i, buf_size);
-                       ret = buf_size;
-               } else {
+       if (!do_mmap) {
+               for (i = 0; i < count; i++) {
                        ret = pread(fd, buf, buf_size, offset + buf_size * i);
-               }
-               if (ret != buf_size)
-                       break;
+                       if (ret != buf_size)
+                               break;
 
-               read_cnt += ret;
-               if (i == 0)
-                       memcpy(print_buf, buf, print_bytes);
+                       read_cnt += ret;
+                       if (i == 0)
+                               memcpy(print_buf, buf, print_bytes);
+               }
+       } else {
+               read_cnt = count * buf_size;
+               memcpy(print_buf, data, print_bytes);
        }
-       printf("Read %"PRIu64" bytes and print %u bytes:\n", read_cnt, 
print_bytes);
+       printf("Read %"PRIu64" bytes total_time = %"PRIu64" us, print %u 
bytes:\n",
+               read_cnt, get_current_us() - total_time, print_bytes);
        printf("%08"PRIx64" : ", offset);
        for (i = 1; i <= print_bytes; i++) {
                printf("%02x", print_buf[i - 1]);
-- 
2.41.0.694.ge786442a9b-goog



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