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Check the page table before TLB1 in pmap_kextract()

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The vast majority of pmap_kextract() calls are looking for a physical memory
address, not a device address.  By checking the page table first this saves
the formerly inevitable 64 (on e500mc and derivatives) iteration loop
through TLB1 in the most common cases.

Benchmarking this on the P5020 (e5500 core) yields a 300% throughput
improvement on dtsec(4) (115Mbit/s -> 460Mbit/s) measured with iperf.

Benchmarked on the P1022 (e500v2 core, 16 TLB1 entries) yields a 50%
throughput improvement on tsec(4) (~93Mbit/s -> 165Mbit/s) measured with
iperf.

MFC after:	1 week
Relnotes:	Maybe (significant performance improvement)
This commit is contained in:
Justin Hibbits 2017-11-21 03:12:16 +00:00
parent e60ff6a3b4
commit 1ccb14588b
1 changed files with 13 additions and 8 deletions
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21
sys/powerpc/booke/pmap.c
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@ -2089,18 +2089,23 @@ static vm_paddr_t
mmu_booke_kextract(mmu_t mmu, vm_offset_t va)
{
tlb_entry_t e;
vm_paddr_t p;
int i;
/* Check TLB1 mappings */
for (i = 0; i < TLB1_ENTRIES; i++) {
tlb1_read_entry(&e, i);
if (!(e.mas1 & MAS1_VALID))
continue;
if (va >= e.virt && va < e.virt + e.size)
return (e.phys + (va - e.virt));
p = pte_vatopa(mmu, kernel_pmap, va);
if (p == 0) {
/* Check TLB1 mappings */
for (i = 0; i < TLB1_ENTRIES; i++) {
tlb1_read_entry(&e, i);
if (!(e.mas1 & MAS1_VALID))
continue;
if (va >= e.virt && va < e.virt + e.size)
return (e.phys + (va - e.virt));
}
}
return (pte_vatopa(mmu, kernel_pmap, va));
return (p);
}
/*