Bjorn Helgaas <helgaas@xxxxxxxxxx> writes: > On Wed, Aug 08, 2018 at 03:44:03PM +0100, Punit Agrawal wrote: >> Bjorn Helgaas <bhelgaas@xxxxxxxxxx> writes: >> > On Thu, Aug 2, 2018 at 9:33 AM Lorenzo Pieralisi >> > <lorenzo.pieralisi@xxxxxxx> wrote: >> >> On Wed, Aug 01, 2018 at 02:38:51PM -0500, Jeremy Linton wrote: >> >> >> >> Jiang Liu does not work on the kernel anymore so we won't know >> >> anytime soon the reasoning behind commit 965cd0e4a5e5 >> >> >> >> > On 08/01/2018 12:31 PM, Punit Agrawal wrote: >> >> > >Memory for host controller data structures is allocated local to the >> >> > >node to which the controller is associated with. This has been the >> >> > >behaviour since support for ACPI was added in >> >> > >commit 0cb0786bac15 ("ARM64: PCI: Support ACPI-based PCI host controller"). >> >> > >> >> > Which was apparently influenced by: >> >> > >> >> > 965cd0e4a5e5 x86, PCI, ACPI: Use kmalloc_node() to optimize for performance >> >> > >> >> > Was there an actual use-case behind that change? >> >> > >> >> > I think this fixes the immediate boot problem, but if there is any >> >> > perf advantage it seems wise to keep it... Particularly since x86 >> >> > seems to be doing the node sanitation in pci_acpi_root_get_node(). >> >> >> >> I am struggling to see the perf advantage of allocating a struct >> >> that the PCI controller will never read/write from a NUMA node that >> >> is local to the PCI controller, happy to be corrected if there is >> >> a sound rationale behind that. >> > >> > If there is no reason to use kzalloc_node() here, we shouldn't use it. >> > >> > But we should use it (or not use it) consistently across arches. I do >> > not believe there is an arch-specific reason to be different. >> > Currently, pci_acpi_scan_root() uses kzalloc_node() on x86 and arm64, >> > but kzalloc() on ia64. They all ought to be the same. >> >> From my understanding, arm64 use of kzalloc_node() was derived from the >> x86 version. Maybe somebody familiar with behaviour on x86 can provide >> input here. > > If you want to remove use of kzalloc_node(), I'm fine with that as > long as you do it for x86 at the same time (maybe separate patches, > but at least in the same series). > > I don't see any evidence in 965cd0e4a5e5 ("x86, PCI, ACPI: Use > kmalloc_node() to optimize for performance") that it actually improves > performance, so I'd be inclined to just use kzalloc(). Thanks for confirming. I'm happy to add a patch updating x86 use of kzalloc_node() as well. I'll post something once the merge window closes. > > Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html