Make vfio MSI interrupt be non-threaded.

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author	Yunhong Jiang <yunhong.jiang@intel.com>	2015-08-18 11:27:04 -0700
committer	Yunhong Jiang <yunhong.jiang@linux.intel.com>	2015-11-24 16:17:35 -0800
commit	a233b3fef0ef0048071145eb233becffbdf96d0f (patch)
tree	22469d010e89674d1ac4ec9df0eebe1e1b28de8c /kernel/drivers/mfd/palmas.c
parent	6744cd0d1d2faad4e7b345563b91888d32db221e (diff)

Make vfio MSI interrupt be non-threaded.

Currently the vfio msi interrupt is kept as IRQ thread, this is not good for NFV scenerio because in NFV scenerio, we want to inject the interrupt to the guest asap. A threaded IRQ introduces schedule latency. However, this change is like a quick and dirty and may bring potential deadlock, because the spinlock_irqsave() from eventfd_signal() is preemptible in RT kernel, which should not be held on IRQ context. But changing it to be raw_spinlock is bad because it will increase the latency a lot if the eventfd is accessed by user space. The deadlock should be ok since for vfio MSI handler is purely kernel story and the lock is a per-eventfd lock and seems no one else is using it for the vfio msi scenario. Upstream status: discussion https://lkml.org/lkml/2015/10/26/764 Change-Id: Ie4405a5b568aa75ca8c3481eeeea228a486b9794

Diffstat (limited to 'kernel/drivers/mfd/palmas.c')

0 files changed, 0 insertions, 0 deletions

# Copyright (c) 2013 Hewlett-Packard Development Company, L.P. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or # implied. # See the License for the specific language governing permissions and # limitations under the License. from setuptools.command.test import test from setuptools import setup import sys class Tox(test): def initialize_options(self): test.initialize_options(self) self.tox_args = None def finalize_options(self): test.finalize_options(self) self.test_args = [] self.test_suite = True def run_tests(self): import tox sys.exit(tox.cmdline()) if __name__ == '__main__': setup(setup_requires=['pbr'], pbr=True, tests_require=['tox'], cmdclass={'test': Tox})


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