Hi, I was wondering what did happen to this patch submission... It seems like Stefan did put a lot of effort in addressing every reported issue for several weeks/months... and then nothing... as if this patch has never been reviewed by anyone... has it been decided to not integrate NAPI busy looping in io_uring privately finally? On Thu, 2023-06-08 at 09:38 -0700, Stefan Roesch wrote: > This adds the napi busy polling support in io_uring.c. It adds a new > napi_list to the io_ring_ctx structure. This list contains the list > of > napi_id's that are currently enabled for busy polling. This list is > used to determine which napi id's enabled busy polling. For faster > access it also adds a hash table. > > When a new napi id is added, the hash table is used to locate if > the napi id has already been added. When processing the busy poll > loop the list is used to process the individual elements. > > io-uring allows specifying two parameters: > - busy poll timeout and > - prefer busy poll to call of io_napi_busy_loop() > This sets the above parameters for the ring. The settings are passed > with a new structure io_uring_napi. > > There is also a corresponding liburing patch series, which enables > this > feature. The name of the series is "liburing: add add api for napi > busy > poll timeout". It also contains two programs to test the this. > > Testing has shown that the round-trip times are reduced to 38us from > 55us by enabling napi busy polling with a busy poll timeout of 100us. > More detailled results are part of the commit message of the first > patch. > > Changes: > - V15: > - Combined _napi_busy_loop() and __napi_busy_loop() function > - Rephrased comment > - V14: > - Rephrased comment for napi_busy_loop_rcu() funnction > - Added new function _napi_busy_loop() to remove code > duplication in napi_busy_loop() and napi_busy_loop_rcu() > - V13: > - split off __napi_busy_loop() from napi_busy_loop() > - introduce napi_busy_loop_no_lock() > - use napi_busy_loop_no_lock in io_napi_blocking_busy_loop > - V12: > - introduce io_napi_hash_find() > - use rcu for changes to the hash table > - use rcu for searching if a napi id is in the napi hash table > - use rcu hlist functions for adding and removing items from the > hash > table > - add stale entry detection in __io_napi_do_busy_loop and remove > stale > entries in io_napi_blocking_busy_loop() and > io_napi_sqpoll_busy_loop() > - create io_napi_remove_stale() and __io_napi_remove_stale() > - __io_napi_do_busy_loop() takes additional loop_end_arg and does > stale > entry detection > - io_napi_multi_busy_loop is removed. Logic is moved to > io_napi_blocking_busy_loop() > - io_napi_free uses rcu function to free > - io_napi_busy_loop no longer splices > - io_napi_sqpoll_busy_poll uses rcu > - V11: > - Fixed long comment lines and whitespace issues > - Refactor new code io_cqring_wait() > - Refactor io_napi_adjust_timeout() and remove adjust_timeout > - Rename io_napi_adjust_timeout to __io_napi_adjust_timeout > - Add new function io_napi_adjust_timeout > - Cleanup calls to list_is_singular() in io_napi_multi_busy_loop() > and io_napi_blocking_busy_loop() > - Cleanup io_napi_busy_loop_should_end() > - Rename __io_napi_busy_loop to __io_napi_do_busy_loop() > - V10: > - Refreshed to io-uring/for-6.4 > - Repeated performance measurements for 6.4 (same/similar results) > - V9: > - refreshed to io-uring/for-6.3 > - folded patch 2 and 3 into patch 4 > - fixed commit description for last 2 patches > - fixed some whitespace issues > - removed io_napi_busy_loop_on helper > - removed io_napi_setup_busy helper > - renamed io_napi_end_busy_loop to io_napi_busy_loop > - removed NAPI_LIST_HEAD macro > - split io_napi_blocking_busy_loop into two functions > - added io_napi function > - comment for sqpoll check > - V8: > - added new file napi.c and add napi functions to this file > - added NAPI_LIST_HEAD function so no ifdef is necessary > - added io_napi_init and io_napi_free function > - added io_napi_setup_busy loop helper function > - added io_napi_adjust_busy_loop helper function > - added io_napi_end_busy_loop helper function > - added io_napi_sqpoll_busy_poll helper function > - some of the definitions in napi.h are macros to avoid ifdef > definitions in io_uring.c, poll.c and sqpoll.c > - changed signature of io_napi_add function > - changed size of hashtable to 16. The number of entries is limited > by the number of nic queues. > - Removed ternary in io_napi_blocking_busy_loop > - Rewrote io_napi_blocking_busy_loop to make it more readable > - Split off 3 more patches > - V7: > - allow unregister with NULL value for arg parameter > - return -EOPNOTSUPP if CONFIG_NET_RX_BUSY_POLL is not enabled > - V6: > - Add a hash table on top of the list for faster access during the > add operation. The linked list and the hash table use the same > data structure > - V5: > - Refreshed to 6.1-rc6 > - Use copy_from_user instead of memdup/kfree > - Removed the moving of napi_busy_poll_to > - Return -EINVAL if any of the reserved or padded fields are not 0. > - V4: > - Pass structure for napi config, instead of individual parameters > - V3: > - Refreshed to 6.1-rc5 > - Added a new io-uring api for the prefer napi busy poll api and > wire > it to io_napi_busy_loop(). > - Removed the unregister (implemented as register) > - Added more performance results to the first commit message. > - V2: > - Add missing defines if CONFIG_NET_RX_BUSY_POLL is not defined > - Changes signature of function io_napi_add_list to static inline > if CONFIG_NET_RX_BUSY_POLL is not defined > - define some functions as static > > > Stefan Roesch (7): > net: split off __napi_busy_poll from napi_busy_poll > net: add napi_busy_loop_rcu() > io-uring: move io_wait_queue definition to header file > io-uring: add napi busy poll support > io-uring: add sqpoll support for napi busy poll > io_uring: add register/unregister napi function > io_uring: add prefer busy poll to register and unregister napi api > > include/linux/io_uring_types.h | 11 ++ > include/net/busy_poll.h | 4 + > include/uapi/linux/io_uring.h | 12 ++ > io_uring/Makefile | 1 + > io_uring/io_uring.c | 41 ++-- > io_uring/io_uring.h | 26 +++ > io_uring/napi.c | 331 > +++++++++++++++++++++++++++++++++ > io_uring/napi.h | 104 +++++++++++ > io_uring/poll.c | 2 + > io_uring/sqpoll.c | 4 + > net/core/dev.c | 34 +++- > 11 files changed, 544 insertions(+), 26 deletions(-) > create mode 100644 io_uring/napi.c > create mode 100644 io_uring/napi.h > > > base-commit: f026be0e1e881e3395c3d5418ffc8c2a2203c3f3
