Hi,
Patch 1 here is the real meat of this, patch 2 is just a slight
improvement. For patch 1, it can literally yield a 50-80x improvement
on the io_uring side for idle systems, where ppoll() ends up sleeping
for 500 msec while there's IO to submit! I noticed this running the
io_uring regression tests in a vm, where I use a variety of block
devices for some of the tests. They would often randomly time out on
AHCI devices, while running them on a virtio-blk or nvme device would
finish in one second or so. I then wrote a reproducer to try and grok
this and had claude dive into this, which helped me better grasp the
various event loops.
Please take a look and tell me what you think. Some variant of patch 1
should definitely be considered, but let me know if this is the right
approach. I can easily test anything.
Also note - this seems to trigger more easily or consistently on
aarch64, which is where I run most of my local/immediate testing.
util/fdmon-io_uring.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)
--
Jens Axboe