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Improve hash coverage for kernel page table entries by modifying the kernel

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ESID -> VSID map function. This makes ZFS run stably on PowerPC under
heavy loads (repeated simultaneous SVN checkouts and updates).
This commit is contained in:
Nathan Whitehorn 2010-07-31 21:35:15 +00:00
parent 19291ab3de
commit 3b4b38304e
3 changed files with 10 additions and 16 deletions
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2
sys/powerpc/aim/mmu_oea64.c
View file

@ -838,7 +838,7 @@ moea64_bootstrap_slb_prefault(vm_offset_t va, int large)
}
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;

11
sys/powerpc/aim/slb.c
View file

@ -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

13
sys/powerpc/include/slb.h
View file

@ -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*/