PCI: Provide Kconfig option for lockless config space accessors
The generic PCI configuration space accessors are globally serialized via
pci_lock. On larger systems this causes massive lock contention when the
configuration space has to be accessed frequently. One such access pattern
is the Intel Uncore performance counter unit.
Provide a kernel config option which can be selected by an architecture
when the low level PCI configuration space accessors in the architecture
use their own serialization or can operate completely lockless.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <helgaas@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: linux-pci@vger.kernel.org
Link: http://lkml.kernel.org/r/20170316215057.205961140@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index e0cacb7..c32a77fc 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -86,6 +86,9 @@
config PCI_ECAM
bool
+config PCI_LOCKLESS_CONFIG
+ bool
+
config PCI_IOV
bool "PCI IOV support"
depends on PCI