svn commit: r326045 - head/sys/powerpc/booke

[Justin Hibbits]

Author: jhibbits
Date: Tue Nov 21 03:12:16 2017
New Revision: 326045
URL: https://svnweb.freebsd.org/changeset/base/326045

Log:
  Check the page table before TLB1 in pmap_kextract()
  
  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)

Modified:
  head/sys/powerpc/booke/pmap.c

Modified: head/sys/powerpc/booke/pmap.c
==============================================================================
--- head/sys/powerpc/booke/pmap.c	Tue Nov 21 02:09:59 2017	(r326044)
+++ head/sys/powerpc/booke/pmap.c	Tue Nov 21 03:12:16 2017	(r326045)
@@ -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);
 }
 
 /*