On 7/20/22 11:24 AM, Jens Axboe wrote:
> On 7/19/22 2:58 AM, Yin Fengwei wrote:
>> Hi Jens,
>>
>> On 7/19/2022 10:29 AM, Jens Axboe wrote:
>>> I'll poke at this tomorrow.
>>
>> Just FYI. Another finding (test is based on commit 584b0180f0):
>> If the code block is put to different function, the fio performance result is
>> different:
>
> I think this turned out to be a little bit of a goose chase. What's
> happening here is that later kernels defer the file assignment, which
> means it isn't set if a request is queued with IOSQE_ASYNC. That in
> turn, for writes, means that we don't hash it on io-wq insertion, and
> then it doesn't get serialized with other writes to that file.
>
> I'll come up with a patch for this that you can test.
Can you try this? It's against 5.19-rc7.
diff --git a/fs/io_uring.c b/fs/io_uring.c
index a01ea49f3017..34758e95990a 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2015,6 +2015,64 @@ static inline void io_arm_ltimeout(struct io_kiocb *req)
__io_arm_ltimeout(req);
}
+static bool io_bdev_nowait(struct block_device *bdev)
+{
+ return !bdev || blk_queue_nowait(bdev_get_queue(bdev));
+}
+
+/*
+ * If we tracked the file through the SCM inflight mechanism, we could support
+ * any file. For now, just ensure that anything potentially problematic is done
+ * inline.
+ */
+static bool __io_file_supports_nowait(struct file *file, umode_t mode)
+{
+ if (S_ISBLK(mode)) {
+ if (IS_ENABLED(CONFIG_BLOCK) &&
+ io_bdev_nowait(I_BDEV(file->f_mapping->host)))
+ return true;
+ return false;
+ }
+ if (S_ISSOCK(mode))
+ return true;
+ if (S_ISREG(mode)) {
+ if (IS_ENABLED(CONFIG_BLOCK) &&
+ io_bdev_nowait(file->f_inode->i_sb->s_bdev) &&
+ file->f_op != &io_uring_fops)
+ return true;
+ return false;
+ }
+
+ /* any ->read/write should understand O_NONBLOCK */
+ if (file->f_flags & O_NONBLOCK)
+ return true;
+ return file->f_mode & FMODE_NOWAIT;
+}
+
+static inline bool io_file_supports_nowait(struct io_kiocb *req)
+{
+ return req->flags & REQ_F_SUPPORT_NOWAIT;
+}
+
+/*
+ * If we tracked the file through the SCM inflight mechanism, we could support
+ * any file. For now, just ensure that anything potentially problematic is done
+ * inline.
+ */
+static unsigned int io_file_get_flags(struct file *file)
+{
+ umode_t mode = file_inode(file)->i_mode;
+ unsigned int res = 0;
+
+ if (S_ISREG(mode))
+ res |= FFS_ISREG;
+ if (__io_file_supports_nowait(file, mode))
+ res |= FFS_NOWAIT;
+ if (io_file_need_scm(file))
+ res |= FFS_SCM;
+ return res;
+}
+
static void io_prep_async_work(struct io_kiocb *req)
{
const struct io_op_def *def = &io_op_defs[req->opcode];
@@ -2031,6 +2089,9 @@ static void io_prep_async_work(struct io_kiocb *req)
if (req->flags & REQ_F_FORCE_ASYNC)
req->work.flags |= IO_WQ_WORK_CONCURRENT;
+ if (req->file && !io_req_ffs_set(req))
+ req->flags |= io_file_get_flags(req->file) << REQ_F_SUPPORT_NOWAIT_BIT;
+
if (req->flags & REQ_F_ISREG) {
if (def->hash_reg_file || (ctx->flags & IORING_SETUP_IOPOLL))
io_wq_hash_work(&req->work, file_inode(req->file));
@@ -3556,64 +3617,6 @@ static void io_iopoll_req_issued(struct io_kiocb *req, unsigned int issue_flags)
}
}
-static bool io_bdev_nowait(struct block_device *bdev)
-{
- return !bdev || blk_queue_nowait(bdev_get_queue(bdev));
-}
-
-/*
- * If we tracked the file through the SCM inflight mechanism, we could support
- * any file. For now, just ensure that anything potentially problematic is done
- * inline.
- */
-static bool __io_file_supports_nowait(struct file *file, umode_t mode)
-{
- if (S_ISBLK(mode)) {
- if (IS_ENABLED(CONFIG_BLOCK) &&
- io_bdev_nowait(I_BDEV(file->f_mapping->host)))
- return true;
- return false;
- }
- if (S_ISSOCK(mode))
- return true;
- if (S_ISREG(mode)) {
- if (IS_ENABLED(CONFIG_BLOCK) &&
- io_bdev_nowait(file->f_inode->i_sb->s_bdev) &&
- file->f_op != &io_uring_fops)
- return true;
- return false;
- }
-
- /* any ->read/write should understand O_NONBLOCK */
- if (file->f_flags & O_NONBLOCK)
- return true;
- return file->f_mode & FMODE_NOWAIT;
-}
-
-/*
- * If we tracked the file through the SCM inflight mechanism, we could support
- * any file. For now, just ensure that anything potentially problematic is done
- * inline.
- */
-static unsigned int io_file_get_flags(struct file *file)
-{
- umode_t mode = file_inode(file)->i_mode;
- unsigned int res = 0;
-
- if (S_ISREG(mode))
- res |= FFS_ISREG;
- if (__io_file_supports_nowait(file, mode))
- res |= FFS_NOWAIT;
- if (io_file_need_scm(file))
- res |= FFS_SCM;
- return res;
-}
-
-static inline bool io_file_supports_nowait(struct io_kiocb *req)
-{
- return req->flags & REQ_F_SUPPORT_NOWAIT;
-}
-
static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct kiocb *kiocb = &req->rw.kiocb;
--
Jens Axboe
