Currently, VFIO takes uses a free-then-request-irq way to do interrupt affinity setting and masking/unmasking for a VM (with device passthru via VFIO). Sometimes only change the cookie data of irqaction or even change nothing. The free-then-request-irq not only adds more latency, but also increases the risk of losing interrupt, which may lead to a VM hung forever in waiting for IO completion
This patchset solved the issue by: Patch 2 introduces irq_update_devid() to only update dev_id of irqaction Patch 3 make use of this function and optimize irq operations in VFIO changes from v3: - rename the new function to irq_update_devid() - amend commit messages and code comments - use disbale_irq()/enable_irq() to avoid a twist for threaded interrupt - add more comments to vfio-pci code changes from v2: - reformat to avoid quoted string split across lines and etc. changes from v1: - add Patch 1 to enhance error recovery etc. in free irq per tglx's comments - enhance error recovery code and debugging info in irq_update_devid - use __must_check in external referencing of this function - use EXPORT_SYMBOL_GPL for irq_update_devid - reformat code of patch 3 for better readability Ben Luo (3): genirq: enhance error recovery code in free irq genirq: introduce irq_update_devid() vfio/pci: make use of irq_update_devid and optimize irq ops drivers/vfio/pci/vfio_pci_intrs.c | 112 +++++++++++++++++++++++++------------- include/linux/interrupt.h | 3 + kernel/irq/manage.c | 105 +++++++++++++++++++++++++++++++---- 3 files changed, 170 insertions(+), 50 deletions(-) -- 1.8.3.1
