| Message ID | 42397f8cd0419694797c6c5cf65ed715117fc760.1682615447.git.reinette.chatre@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vfio/pci: Support dynamic allocation of MSI-X interrupts | expand |
> From: Chatre, Reinette <reinette.chatre@intel.com> > Sent: Friday, April 28, 2023 1:36 AM > > struct vfio_pci_core_device contains eleven boolean flags. > Boolean flags clearly indicate their usage but space usage > starts to be a concern when there are many. > > An upcoming change adds another boolean flag to > struct vfio_pci_core_device, thereby increasing the concern > that the boolean flags are consuming unnecessary space. > > Transition the boolean flags to use bitfields. On a system that > uses one byte per boolean this reduces the space consumed > by existing flags from 11 bytes to 2 bytes with room for > a few more flags without increasing the structure's size. > > Suggested-by: Jason Gunthorpe <jgg@nvidia.com> > Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h index 148fd1ae6c1c..adb47e2914d7 100644 --- a/include/linux/vfio_pci_core.h +++ b/include/linux/vfio_pci_core.h @@ -68,17 +68,17 @@ struct vfio_pci_core_device { u16 msix_size; u32 msix_offset; u32 rbar[7]; - bool pci_2_3; - bool virq_disabled; - bool reset_works; - bool extended_caps; - bool bardirty; - bool has_vga; - bool needs_reset; - bool nointx; - bool needs_pm_restore; - bool pm_intx_masked; - bool pm_runtime_engaged; + bool pci_2_3:1; + bool virq_disabled:1; + bool reset_works:1; + bool extended_caps:1; + bool bardirty:1; + bool has_vga:1; + bool needs_reset:1; + bool nointx:1; + bool needs_pm_restore:1; + bool pm_intx_masked:1; + bool pm_runtime_engaged:1; struct pci_saved_state *pci_saved_state; struct pci_saved_state *pm_save; int ioeventfds_nr;
struct vfio_pci_core_device contains eleven boolean flags. Boolean flags clearly indicate their usage but space usage starts to be a concern when there are many. An upcoming change adds another boolean flag to struct vfio_pci_core_device, thereby increasing the concern that the boolean flags are consuming unnecessary space. Transition the boolean flags to use bitfields. On a system that uses one byte per boolean this reduces the space consumed by existing flags from 11 bytes to 2 bytes with room for a few more flags without increasing the structure's size. Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> --- Changes since V3: - New patch. (Jason) include/linux/vfio_pci_core.h | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)