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helo=mail-ot1-x32e.google.com","X-Spam_score_int":"-18","X-Spam_score":"-1.9","X-Spam_bar":"-","X-Spam_report":"(-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Hi,\n\nPatch 1 here is the real meat of this, patch 2 is just a slight\nimprovement. For patch 1, it can literally yield a 50-80x improvement\non the io_uring side for idle systems, where ppoll() ends up sleeping\nfor 500 msec while there's IO to submit! I noticed this running the\nio_uring regression tests in a vm, where I use a variety of block\ndevices for some of the tests. They would often randomly time out on\nAHCI devices, while running them on a virtio-blk or nvme device would\nfinish in one second or so. I then wrote a reproducer to try and grok\nthis and had claude dive into this, which helped me better grasp the\nvarious event loops.\n\nPlease take a look and tell me what you think. Some variant of patch 1\nshould definitely be considered, but let me know if this is the right\napproach. I can easily test anything.\n\nAlso note - this seems to trigger more easily or consistently on\naarch64, which is where I run most of my local/immediate testing.\n\n util/fdmon-io_uring.c | 22 +++++++++++++++++++++-\n 1 file changed, 21 insertions(+), 1 deletion(-)"}