Author: nwhitehorn
Date: Sat Jul 31 21:35:15 2010
New Revision: 210704
URL: http://svn.freebsd.org/changeset/base/210704
Log:
Improve hash coverage for kernel page table entries by modifying the kernel
ESID -> VSID map function. This makes ZFS run stably on PowerPC under
heavy loads (repeated simultaneous SVN checkouts and updates).
Modified:
head/sys/powerpc/aim/mmu_oea64.c
head/sys/powerpc/aim/slb.c
head/sys/powerpc/include/slb.h
Modified: head/sys/powerpc/aim/mmu_oea64.c
==============================================================================
--- head/sys/powerpc/aim/mmu_oea64.c Sat Jul 31 21:33:18 2010
(r210703)
+++ head/sys/powerpc/aim/mmu_oea64.c Sat Jul 31 21:35:15 2010
(r210704)
@@ -838,7 +838,7 @@ moea64_bootstrap_slb_prefault(vm_offset_
}
entry.slbe = slbe;
- entry.slbv = KERNEL_VSID(esid, large) << SLBV_VSID_SHIFT;
+ entry.slbv = KERNEL_VSID(esid) << SLBV_VSID_SHIFT;
if (large)
entry.slbv |= SLBV_L;
Modified: head/sys/powerpc/aim/slb.c
==============================================================================
--- head/sys/powerpc/aim/slb.c Sat Jul 31 21:33:18 2010 (r210703)
+++ head/sys/powerpc/aim/slb.c Sat Jul 31 21:35:15 2010 (r210704)
@@ -104,17 +104,10 @@ uint64_t
va_to_vsid(pmap_t pm, vm_offset_t va)
{
struct slb entry;
- int large;
/* Shortcut kernel case */
- if (pm == kernel_pmap) {
- large = 0;
- if (hw_direct_map && va < VM_MIN_KERNEL_ADDRESS &&
- mem_valid(va, 0) == 0)
- large = 1;
-
- return (KERNEL_VSID((uintptr_t)va >> ADDR_SR_SHFT, large));
- }
+ if (pm == kernel_pmap)
+ return (KERNEL_VSID((uintptr_t)va >> ADDR_SR_SHFT));
/*
* If there is no vsid for this VA, we need to add a new entry
Modified: head/sys/powerpc/include/slb.h
==============================================================================
--- head/sys/powerpc/include/slb.h Sat Jul 31 21:33:18 2010
(r210703)
+++ head/sys/powerpc/include/slb.h Sat Jul 31 21:35:15 2010
(r210704)
@@ -47,14 +47,15 @@
#define SLBV_VSID_MASK 0xfffffffffffff000UL /* Virtual segment ID mask
*/
#define SLBV_VSID_SHIFT 12
-#define KERNEL_VSID_BIT 0x0000001000000000UL /* Bit set in all kernel
VSIDs */
-
/*
- * Shift large-page VSIDs one place left. At present, they are only used in the
- * kernel direct map, and we already assume in the placement of KVA that the
- * CPU cannot address more than 63 bits of memory.
+ * Make a predictable 1:1 map from ESIDs to VSIDs for the kernel. Hash table
+ * coverage is increased by swizzling the ESID and multiplying by a prime
+ * number (0x13bb).
*/
-#define KERNEL_VSID(esid, large) (((uint64_t)(esid) << (large ? 1 : 0)) |
KERNEL_VSID_BIT)
+#define KERNEL_VSID_BIT 0x0000001000000000UL /* Bit set in all kernel
VSIDs */
+#define KERNEL_VSID(esid) ((((((uint64_t)esid << 8) | ((uint64_t)esid >> 28)) \
+ * 0x13bbUL) & (KERNEL_VSID_BIT - 1)) | \
+ KERNEL_VSID_BIT)
#define SLBE_VALID 0x0000000008000000UL /* SLB entry valid */
#define SLBE_INDEX_MASK 0x0000000000000fffUL /* SLB index mask*/
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