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  1. 13 9月, 2019 2 次提交
  3. 10 9月, 2019 5 次提交
    • J
      io_uring: limit parallelism of buffered writes · 54a91f3b
      由 Jens Axboe 提交于 
      All the popular filesystems need to grab the inode lock for buffered
writes. With io_uring punting buffered writes to async context, we
observe a lot of contention with all workers hamming this mutex.

For buffered writes, we generally don't need a lot of parallelism on
the submission side, as the flushing will take care of that for us.
Hence we don't need a deep queue on the write side, as long as we
can safely punt from the original submission context.

Add a workqueue with a limit of 2 that we can use for buffered writes.
This greatly improves the performance and efficiency of higher queue
depth buffered async writes with io_uring.
Reported-by: NAndres Freund <andres@anarazel.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      54a91f3b
    • J
      io_uring: add io_queue_async_work() helper · 18d9be1a
      由 Jens Axboe 提交于 
      Add a helper for queueing a request for async execution, in preparation
for optimizing it.

No functional change in this patch.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      18d9be1a
    • J
      io_uring: optimize submit_and_wait API · c5766668
      由 Jens Axboe 提交于 
      For some applications that end up using a submit-and-wait type of
approach for certain batches of IO, we can make that a bit more
efficient by allowing the application to block for the last IO
submission. This prevents an async when we don't need it, as the
application will be blocking for the completion event(s) anyway.

Typical use cases are using the liburing
io_uring_submit_and_wait() API, or just using io_uring_enter()
doing both submissions and completions. As a specific example,
RocksDB doing MultiGet() is sped up quite a bit with this
change.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      c5766668
    • J
      io_uring: add support for link with drain · 4fe2c963
      由 Jackie Liu 提交于 
      To support the link with drain, we need to do two parts.

There is an sqes:

    0     1     2     3     4     5     6
 +-----+-----+-----+-----+-----+-----+-----+
 |  N  |  L  |  L  | L+D |  N  |  N  |  N  |
 +-----+-----+-----+-----+-----+-----+-----+

First, we need to ensure that the io before the link is completed,
there is a easy way is set drain flag to the link list's head, so
all subsequent io will be inserted into the defer_list.

	+-----+
    (0) |  N  |
	+-----+
           |          (2)         (3)         (4)
	+-----+     +-----+     +-----+     +-----+
    (1) | L+D | --> |  L  | --> | L+D | --> |  N  |
	+-----+     +-----+     +-----+     +-----+
           |
	+-----+
    (5) |  N  |
	+-----+
           |
	+-----+
    (6) |  N  |
	+-----+

Second, ensure that the following IO will not be completed first,
an easy way is to create a mirror of drain io and insert it into
defer_list, in this way, as long as drain io is not processed, the
following io in the defer_list will not be actively process.

	+-----+
    (0) |  N  |
	+-----+
           |          (2)         (3)         (4)
	+-----+     +-----+     +-----+     +-----+
    (1) | L+D | --> |  L  | --> | L+D | --> |  N  |
	+-----+     +-----+     +-----+     +-----+
           |
	+-----+
   ('3) |  D  |   <== This is a shadow of (3)
	+-----+
           |
	+-----+
    (5) |  N  |
	+-----+
           |
	+-----+
    (6) |  N  |
	+-----+
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      4fe2c963
    • J
      io_uring: fix wrong sequence setting logic · 8776f3fa
      由 Jackie Liu 提交于 
      Sqo_thread will get sqring in batches, which will cause
ctx->cached_sq_head to be added in batches. if one of these
sqes is set with the DRAIN flag, then he will never get a
chance to process, and finally sqo_thread will not exit.

Fixes: de0617e4 ("io_uring: add support for marking commands as draining")
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      8776f3fa
  5. 07 9月, 2019 1 次提交
    • J
      io_uring: expose single mmap capability · ac90f249
      由 Jens Axboe 提交于 
      After commit 75b28aff we can get by with just a single mmap to
map both the sq and cq ring. However, userspace doesn't know that.

Add a features variable to io_uring_params, and notify userspace
that the kernel has this ability. This can then be used in liburing
(or in applications directly) to avoid the second mmap.
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      ac90f249
  7. 28 8月, 2019 2 次提交
  9. 26 8月, 2019 10 次提交
  11. 25 8月, 2019 18 次提交
  13. 24 8月, 2019 2 次提交