Flash attention #2711

Job	Run time
build-and-test-cpp-aarch64 (openblas)	4m 8s
build-and-test-cpp-x86_64 (ubuntu-20.04, mkl)	5m 52s
build-and-push-docker-images	39m 39s
build-and-test-cpp-x86_64 (ubuntu-20.04, dnnl)	6m 20s
build-python-wheels (ubuntu-20.04, auto64)	29m 9s
build-and-test-cpp-x86_64 (macos-11, mkl)	10m 32s
check-python-style	8s
build-python-wheels (macos-11, auto64)	29m 6s
build-python-wheels (windows-2019, auto64)	28m 49s
build-python-wheels (ubuntu-20.04, aarch64)	29m 9s
build-and-test-cpp-x86_64 (macos-11, dnnl)	10m 26s
build-python-wheels (macos-11, arm64)	12m 37s
test-python-wheels	0s
build-and-deploy-docs	0s
publish-python-wheels-on-pypi	0s
	3h 25m 55s

Provide feedback