Messages in this thread | | | Date | Tue, 24 Oct 2023 19:58:50 +0800 | Subject | Re: [PATCH 1/2] iommu: Introduce a rb_tree for looking up device | From | Baolu Lu <> |
| |
On 2023/10/24 16:41, Huang Jiaqing wrote: > The existing IO page fault handler locates the PCI device by calling > pci_get_domain_bus_and_slot(), which searches the list of all PCI > devices until the desired PCI device is found. This is inefficient > because the algorithm efficiency of searching a list is O(n). In the > critical path of handling an IO page fault, this is not performance > friendly given that I/O page fault handling patch is performance > critical, and parallel heavy dsa_test may cause cpu stuck due to > the low efficiency and lock competition in current path. > > To improve the performance of the IO page fault handler, replace > pci_get_domain_bus_and_slot() with a local red-black tree. A red-black > tree is a self-balancing binary search tree, which means that the > average time complexity of searching a red-black tree is O(log(n)). This > is significantly faster than O(n), so it can significantly improve the > performance of the IO page fault handler. > > In addition, we can only insert the affected devices (those that have IO > page fault enabled) into the red-black tree. This can further improve > the performance of the IO page fault handler. > > This series depends on "deliver page faults to user space" patch-set: > https://lore.kernel.org/linux-iommu/20230928042734.16134-1-baolu.lu@linux.intel.com/
The note above is not part of the commit message, and should be placed below the tear line or in the cover letter, if there is one.
> > Signed-off-by: Huang Jiaqing <jiaqing.huang@intel.com> > --- > drivers/iommu/io-pgfault.c | 104 ++++++++++++++++++++++++++++++++++++- > include/linux/iommu.h | 16 ++++++ > 2 files changed, 118 insertions(+), 2 deletions(-)
Best regards, baolu
| |