Re: [PATCH v4] KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule

2014-06-24 Thread Alexander Graf 


On 18.06.14 09:15, Mihai Caraman wrote:

On vcpu schedule, the condition checked for tlb pollution is too loose.
The tlb entries of a vcpu become polluted (vs stale) only when a different
vcpu within the same logical partition runs in-between. Optimize the tlb
invalidation condition keeping last_vcpu per logical partition id.

With the new invalidation condition, a guest shows 4% performance improvement
on P5020DS while running a memory stress application with the cpu 
oversubscribed,
the other guest running a cpu intensive workload.

Guest - old invalidation condition
   real 3.89
   user 3.87
   sys 0.01

Guest - enhanced invalidation condition
   real 3.75
   user 3.73
   sys 0.01

Host
   real 3.70
   user 1.85
   sys 0.00

The memory stress application accesses 4KB pages backed by 75% of available
TLB0 entries:

char foo[ENTRIES][4096] __attribute__ ((aligned (4096)));

int main()
{
char bar;
int i, j;

for (i = 0; i  ITERATIONS; i++)
for (j = 0; j  ENTRIES; j++)
bar = foo[j][0];

return 0;
}

Signed-off-by: Mihai Caraman mihai.cara...@freescale.com
Cc: Scott Wood scottw...@freescale.com


Thanks, applied to kvm-ppc-queue.


Alex

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[PATCH v4] KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule

2014-06-18 Thread Mihai Caraman 
On vcpu schedule, the condition checked for tlb pollution is too loose.
The tlb entries of a vcpu become polluted (vs stale) only when a different
vcpu within the same logical partition runs in-between. Optimize the tlb
invalidation condition keeping last_vcpu per logical partition id.

With the new invalidation condition, a guest shows 4% performance improvement
on P5020DS while running a memory stress application with the cpu 
oversubscribed,
the other guest running a cpu intensive workload.

Guest - old invalidation condition
  real 3.89
  user 3.87
  sys 0.01

Guest - enhanced invalidation condition
  real 3.75
  user 3.73
  sys 0.01

Host
  real 3.70
  user 1.85
  sys 0.00

The memory stress application accesses 4KB pages backed by 75% of available
TLB0 entries:

char foo[ENTRIES][4096] __attribute__ ((aligned (4096)));

int main()
{
char bar;
int i, j;

for (i = 0; i  ITERATIONS; i++)
for (j = 0; j  ENTRIES; j++)
bar = foo[j][0];

return 0;
}

Signed-off-by: Mihai Caraman mihai.cara...@freescale.com
Cc: Scott Wood scottw...@freescale.com
---
v4:
 - rename last_vcpu_on_cpu to last_vcpu_of_lpid
 - use *[ syntax despite checkpatch error
 
v3:
 - use existing logic while keeping last_cpu per lpid

 arch/powerpc/kvm/e500mc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
index 17e4562..690499d 100644
--- a/arch/powerpc/kvm/e500mc.c
+++ b/arch/powerpc/kvm/e500mc.c
@@ -110,7 +110,7 @@ void kvmppc_mmu_msr_notify(struct kvm_vcpu *vcpu, u32 
old_msr)
 {
 }
 
-static DEFINE_PER_CPU(struct kvm_vcpu *, last_vcpu_on_cpu);
+static DEFINE_PER_CPU(struct kvm_vcpu *[KVMPPC_NR_LPIDS], last_vcpu_of_lpid);
 
 static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu)
 {
@@ -141,9 +141,9 @@ static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu 
*vcpu, int cpu)
mtspr(SPRN_GESR, vcpu-arch.shared-esr);
 
if (vcpu-arch.oldpir != mfspr(SPRN_PIR) ||
-   __get_cpu_var(last_vcpu_on_cpu) != vcpu) {
+   __get_cpu_var(last_vcpu_of_lpid)[vcpu-kvm-arch.lpid] != vcpu) {
kvmppc_e500_tlbil_all(vcpu_e500);
-   __get_cpu_var(last_vcpu_on_cpu) = vcpu;
+   __get_cpu_var(last_vcpu_of_lpid)[vcpu-kvm-arch.lpid] = vcpu;
}
 
kvmppc_load_guest_fp(vcpu);
-- 
1.7.11.7

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Re: [PATCH v4] KVM: PPC: e500mc: Enhance tlb invalidation condition on vcpu schedule

2014-06-18 Thread Scott Wood 
On Wed, 2014-06-18 at 10:15 +0300, Mihai Caraman wrote:
 On vcpu schedule, the condition checked for tlb pollution is too loose.
 The tlb entries of a vcpu become polluted (vs stale) only when a different
 vcpu within the same logical partition runs in-between. Optimize the tlb
 invalidation condition keeping last_vcpu per logical partition id.
 
 With the new invalidation condition, a guest shows 4% performance improvement
 on P5020DS while running a memory stress application with the cpu 
 oversubscribed,
 the other guest running a cpu intensive workload.
 
 Guest - old invalidation condition
   real 3.89
   user 3.87
   sys 0.01
 
 Guest - enhanced invalidation condition
   real 3.75
   user 3.73
   sys 0.01
 
 Host
   real 3.70
   user 1.85
   sys 0.00
 
 The memory stress application accesses 4KB pages backed by 75% of available
 TLB0 entries:
 
 char foo[ENTRIES][4096] __attribute__ ((aligned (4096)));
 
 int main()
 {
   char bar;
   int i, j;
 
   for (i = 0; i  ITERATIONS; i++)
   for (j = 0; j  ENTRIES; j++)
   bar = foo[j][0];
 
   return 0;
 }
 
 Signed-off-by: Mihai Caraman mihai.cara...@freescale.com
 Cc: Scott Wood scottw...@freescale.com
 ---
 v4:
  - rename last_vcpu_on_cpu to last_vcpu_of_lpid
  - use *[ syntax despite checkpatch error
  
 v3:
  - use existing logic while keeping last_cpu per lpid
 
  arch/powerpc/kvm/e500mc.c | 6 +++---
  1 file changed, 3 insertions(+), 3 deletions(-)
 
 diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
 index 17e4562..690499d 100644
 --- a/arch/powerpc/kvm/e500mc.c
 +++ b/arch/powerpc/kvm/e500mc.c
 @@ -110,7 +110,7 @@ void kvmppc_mmu_msr_notify(struct kvm_vcpu *vcpu, u32 
 old_msr)
  {
  }
  
 -static DEFINE_PER_CPU(struct kvm_vcpu *, last_vcpu_on_cpu);
 +static DEFINE_PER_CPU(struct kvm_vcpu *[KVMPPC_NR_LPIDS], last_vcpu_of_lpid);
  
  static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu)
  {
 @@ -141,9 +141,9 @@ static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu 
 *vcpu, int cpu)
   mtspr(SPRN_GESR, vcpu-arch.shared-esr);
  
   if (vcpu-arch.oldpir != mfspr(SPRN_PIR) ||
 - __get_cpu_var(last_vcpu_on_cpu) != vcpu) {
 + __get_cpu_var(last_vcpu_of_lpid)[vcpu-kvm-arch.lpid] != vcpu) {
   kvmppc_e500_tlbil_all(vcpu_e500);
 - __get_cpu_var(last_vcpu_on_cpu) = vcpu;
 + __get_cpu_var(last_vcpu_of_lpid)[vcpu-kvm-arch.lpid] = vcpu;
   }
  
   kvmppc_load_guest_fp(vcpu);

Reviewed-by: Scott Wood scottw...@freescale.com

-Scott


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