The sqpoll thread can be used for performing the napi busy poll in a
similar way that it does io polling for file systems supporting direct
access bypassing the page cache.
The other way that io_uring can be used for napi busy poll is by
calling io_uring_enter() to get events.
If the user specify a timeout value, it is distributed between polling
and sleeping by using the systemwide setting
/proc/sys/net/core/busy_poll.
v2:
* Evaluate list_empty(&ctx->napi_list) outside io_napi_busy_loop() to keep
__io_sq_thread() execution as fast as possible
* In io_cqring_wait(), move up the sig block to avoid needless computation
if the block exits the function
* In io_cqring_wait(), protect ctx->napi_list from race condition by
splicing it into a local list
* In io_cqring_wait(), allow busy polling when uts is missing
* Fix kernel test robot issues
v3:
* Fix do_div() type mismatch warning
* Reduce uring_lock contention by creating a spinlock for protecting
napi_list
* Support correctly MULTISHOT poll requests
Co-developed-by: Hao Xu <[email protected]>
Signed-off-by: Hao Xu <[email protected]>
Signed-off-by: Olivier Langlois <[email protected]>
Olivier Langlois (2):
io_uring: minor io_cqring_wait() optimization
io_uring: Add support for napi_busy_poll
fs/io_uring.c | 246 ++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 237 insertions(+), 9 deletions(-)
base-commit: 719fce7539cd3e186598e2aed36325fe892150cf
--
2.35.1