On 5/28/2013 9:27 AM, Alex Williamson wrote:
Add a module option to vfio_iommu_type1 to disable IOMMU hugepage
support. This causes iommu_map to only be called with single page
mappings, disabling the IOMMU driver's ability to use hugepages.
This option can be enabled by loading vfio_iommu_type1 with
disable_hugepages=1 or dynamically through sysfs. If enabled
dynamically, only new mappings are restricted.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
As suggested by Konrad. This is cleaner to add as a follow-on
drivers/vfio/vfio_iommu_type1.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 6654a7e..8a2be4e 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -48,6 +48,12 @@ module_param_named(allow_unsafe_interrupts,
MODULE_PARM_DESC(allow_unsafe_interrupts,
"Enable VFIO IOMMU support for on platforms without interrupt remapping support.");
+static bool disable_hugepages;
+module_param_named(disable_hugepages,
+ disable_hugepages, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(disable_hugepages,
+ "Disable VFIO IOMMU support for IOMMU hugepages.");
+
struct vfio_iommu {
struct iommu_domain *domain;
struct mutex lock;
@@ -270,6 +276,11 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
return -ENOMEM;
}
+ if (unlikely(disable_hugepages)) {
+ vfio_lock_acct(1);
+ return 1;
+ }
+
/* Lock all the consecutive pages from pfn_base */
for (i = 1, vaddr += PAGE_SIZE; i < npage; i++, vaddr += PAGE_SIZE) {
unsigned long pfn = 0;
.
Tested-by: Chegu Vinod <chegu_vinod@xxxxxx>
I was able to verify your changes on a 2 Sandybridge-EP socket platform
and observed about ~7-8% improvement in the netperf's TCP_RR
performance. The guest size was small (16vcpu/32GB).
Hopefully these changes also have an indirect benefit of avoiding soft
lockups on the host side when larger guests (> 256GB ) are rebooted.
Someone who has ready access to a larger Sandybridge-EP/EX platform can
verify this.
FYI
Vinod
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