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io_uring: track io length in async_list based on bytes 

We are using PAGE_SIZE as the unit to determine if the total len in
async_list has exceeded max_pages, it's not fair for smaller io sizes.
For example, if we are doing 1k-size io streams, we will never exceed
max_pages since len >>= PAGE_SHIFT always gets zero. So use original
bytes to make it more accurate.

Signed-off-by: Zhengyuan Liu <liuzhengyuan@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Zhengyuan Liu 2019-07-22 10:23:27 +08:00 committed by Jens Axboe
parent bd11b3a391
commit 9310a7ba6d
1 changed files with 10 additions and 12 deletions
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22
fs/io_uring.c
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@ -202,7 +202,7 @@ struct async_list {
struct file *file;
off_t io_end;
size_t io_pages;
size_t io_len;
};
struct io_ring_ctx {
@ -1158,28 +1158,26 @@ static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
off_t io_end = kiocb->ki_pos + len;
if (filp == async_list->file && kiocb->ki_pos == async_list->io_end) {
unsigned long max_pages;
unsigned long max_bytes;
/* Use 8x RA size as a decent limiter for both reads/writes */
max_pages = filp->f_ra.ra_pages;
if (!max_pages)
max_pages = VM_READAHEAD_PAGES;
max_pages *= 8;
max_bytes = filp->f_ra.ra_pages << (PAGE_SHIFT + 3);
if (!max_bytes)
max_bytes = VM_READAHEAD_PAGES << (PAGE_SHIFT + 3);
/* If max pages are exceeded, reset the state */
len >>= PAGE_SHIFT;
if (async_list->io_pages + len <= max_pages) {
/* If max len are exceeded, reset the state */
if (async_list->io_len + len <= max_bytes) {
req->flags |= REQ_F_SEQ_PREV;
async_list->io_pages += len;
async_list->io_len += len;
} else {
io_end = 0;
async_list->io_pages = 0;
async_list->io_len = 0;
}
}
/* New file? Reset state. */
if (async_list->file != filp) {
async_list->io_pages = 0;
async_list->io_len = 0;
async_list->file = filp;
}
async_list->io_end = io_end;