On Fri, Nov 05, 2021 at 12:56:09PM +0100, Paul Menzel wrote: > Dear Linux folks, > > > On a PowerEdge T440/021KCD, BIOS 2.11.2 04/22/2021, Linux 5.10.70 takes > almost five seconds to initialize PCI. According to the timestamps, 1.5 s > are from assigning the PCI devices to the 142 IOMMU groups. > > ``` > $ lspci | wc -l > 281 > $ dmesg > […] > [ 2.918411] PCI: Using host bridge windows from ACPI; if necessary, use > "pci=nocrs" and report a bug > [ 2.933841] ACPI: Enabled 5 GPEs in block 00 to 7F > [ 2.973739] ACPI: PCI Root Bridge [PC00] (domain 0000 [bus 00-16]) > [ 2.980398] acpi PNP0A08:00: _OSC: OS supports [ExtendedConfig ASPM > ClockPM Segments MSI HPX-Type3] > [ 2.989457] acpi PNP0A08:00: _OSC: platform does not support [LTR] > [ 2.995451] acpi PNP0A08:00: _OSC: OS now controls [PME PCIeCapability] > [ 3.001394] acpi PNP0A08:00: FADT indicates ASPM is unsupported, using > BIOS configuration > [ 3.010511] PCI host bridge to bus 0000:00 > […] > [ 6.233508] system 00:05: [io 0x1000-0x10fe] has been reserved > [ 6.239420] system 00:05: Plug and Play ACPI device, IDs PNP0c02 (active) > [ 6.239906] pnp: PnP ACPI: found 6 devices For ~280 PCI devices, (6.24-2.92)/280 = 0.012 s/dev. On my laptop I have about (.66-.37)/36 = 0.008 s/dev (on v5.4), so about the same ballpark. Faster would always be better, of course. I assume this is not really a regression? > [ 6.989016] pci 0000:d7:05.0: disabled boot interrupts on device > [8086:2034] > [ 6.996063] PCI: CLS 0 bytes, default 64 > [ 7.000008] Trying to unpack rootfs image as initramfs... > [ 7.065281] Freeing initrd memory: 5136K > […] > [ 7.079098] DMAR: dmar7: Using Queued invalidation > [ 7.083983] pci 0000:00:00.0: Adding to iommu group 0 > […] > [ 8.537808] pci 0000:d7:17.1: Adding to iommu group 141 I don't have this iommu stuff turned on and don't know what's happening here. > Is there anything that could be done to reduce the time? > > > Kind regards, > > Paul
