>Hi,
>
>Could you please test this patch?
>
I tried this patch, but the problem still be there.
Thanks,
Zhang Haoyu
>>From 48df7db2ec2721e35d024a8d9850dbb34b557c1c Mon Sep 17 00:00:00 2001
>From: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
>Date: Thu, 6 Sep 2012 16:56:01 +0800
>Subject: [PATCH 10/11] using huge page on fast page fault path
>
>---
> arch/x86/kvm/mmu.c | 27 ++++++++++++++++++++-------
> 1 files changed, 20 insertions(+), 7 deletions(-)
>
>diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>index 6945ef4..7d177c7 100644
>--- a/arch/x86/kvm/mmu.c
>+++ b/arch/x86/kvm/mmu.c
>@@ -2663,6 +2663,13 @@ static int kvm_handle_bad_page(struct kvm_vcpu
*vcpu, gfn_t gfn, pfn_t pfn)
> return -EFAULT;
> }
>
>+static bool pfn_can_adjust(pfn_t pfn, int level)
>+{
>+ return !is_error_pfn(pfn) && !kvm_is_mmio_pfn(pfn) &&
>+ level == PT_PAGE_TABLE_LEVEL &&
>+ PageTransCompound(pfn_to_page(pfn));
>+}
>+
> static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
> gfn_t *gfnp, pfn_t *pfnp, int *levelp)
> {
>@@ -2676,10 +2683,8 @@ static void transparent_hugepage_adjust(struct
kvm_vcpu *vcpu,
> * PT_PAGE_TABLE_LEVEL and there would be no adjustment done
> * here.
> */
>- if (!is_error_pfn(pfn) && !kvm_is_mmio_pfn(pfn) &&
>- level == PT_PAGE_TABLE_LEVEL &&
>- PageTransCompound(pfn_to_page(pfn)) &&
>- !has_wrprotected_page(vcpu->kvm, gfn, PT_DIRECTORY_LEVEL)) {
>+ if (pfn_can_adjust(pfn, level) &&
>+ !has_wrprotected_page(vcpu->kvm, gfn, PT_DIRECTORY_LEVEL)) {
> unsigned long mask;
> /*
> * mmu_notifier_retry was successful and we hold the
>@@ -2768,7 +2773,7 @@ fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu,
u64 *sptep, u64 spte)
> * - false: let the real page fault path to fix it.
> */
> static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
>- u32 error_code)
>+ u32 error_code, bool force_pt_level)
> {
> struct kvm_shadow_walk_iterator iterator;
> bool ret = false;
>@@ -2795,6 +2800,14 @@ static bool fast_page_fault(struct kvm_vcpu
*vcpu, gva_t gva, int level,
> goto exit;
>
> /*
>+ * Let the real page fault path change the mapping if large
>+ * mapping is allowed, for example, the memslot dirty log is
>+ * disabled.
>+ */
>+ if (!force_pt_level && pfn_can_adjust(spte_to_pfn(spte), level))
>+ goto exit;
>+
>+ /*
> * Check if it is a spurious fault caused by TLB lazily flushed.
> *
> * Need not check the access of upper level table entries since
>@@ -2854,7 +2867,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu,
gva_t v, u32 error_code,
> } else
> level = PT_PAGE_TABLE_LEVEL;
>
>- if (fast_page_fault(vcpu, v, level, error_code))
>+ if (fast_page_fault(vcpu, v, level, error_code, force_pt_level))
> return 0;
>
> mmu_seq = vcpu->kvm->mmu_notifier_seq;
>@@ -3323,7 +3336,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu,
gva_t gpa, u32 error_code,
> } else
> level = PT_PAGE_TABLE_LEVEL;
>
>- if (fast_page_fault(vcpu, gpa, level, error_code))
>+ if (fast_page_fault(vcpu, gpa, level, error_code, force_pt_level))
> return 0;
>
> mmu_seq = vcpu->kvm->mmu_notifier_seq;
>-- 1.7.7.6 On 07/11/2013 05:36 PM, Zhanghaoyu (A) wrote:
>> hi all,
>>
>> I met similar problem to these, while performing live migration or
save-restore test on the kvm platform (qemu:1.4.0, host:suse11sp2,
guest:suse11sp2), running tele-communication software suite in guest,
>> https://lists.gnu.org/archive/html/qemu-devel/2013-05/msg00098.html
>> http://comments.gmane.org/gmane.comp.emulators.kvm.devel/102506
>> http://thread.gmane.org/gmane.comp.emulators.kvm.devel/100592
>> https://bugzilla.kernel.org/show_bug.cgi?id=58771
>>
>> After live migration or virsh restore [savefile], one process's CPU
utilization went up by about 30%, resulted in throughput degradation of
this process.
>> oprofile report on this process in guest,
>> pre live migration:
>> CPU: CPU with timer interrupt, speed 0 MHz (estimated)
>> Profiling through timer interrupt
>> samples % app name symbol name
>> 248 12.3016 no-vmlinux (no symbols)
>> 78 3.8690 libc.so.6 memset
>> 68 3.3730 libc.so.6 memcpy
>> 30 1.4881 cscf.scu SipMmBufMemAlloc
>> 29 1.4385 libpthread.so.0 pthread_mutex_lock
>> 26 1.2897 cscf.scu SipApiGetNextIe
>> 25 1.2401 cscf.scu DBFI_DATA_Search
>> 20 0.9921 libpthread.so.0 __pthread_mutex_unlock_usercnt
>> 16 0.7937 cscf.scu DLM_FreeSlice
>> 16 0.7937 cscf.scu receivemessage
>> 15 0.7440 cscf.scu SipSmCopyString
>> 14 0.6944 cscf.scu DLM_AllocSlice
>>
>> post live migration:
>> CPU: CPU with timer interrupt, speed 0 MHz (estimated)
>> Profiling through timer interrupt
>> samples % app name symbol name
>> 1586 42.2370 libc.so.6 memcpy
>> 271 7.2170 no-vmlinux (no symbols)
>> 83 2.2104 libc.so.6 memset
>> 41 1.0919 libpthread.so.0 __pthread_mutex_unlock_usercnt
>> 35 0.9321 cscf.scu SipMmBufMemAlloc
>> 29 0.7723 cscf.scu DLM_AllocSlice
>> 28 0.7457 libpthread.so.0 pthread_mutex_lock
>> 23 0.6125 cscf.scu SipApiGetNextIe
>> 17 0.4527 cscf.scu SipSmCopyString
>> 16 0.4261 cscf.scu receivemessage
>> 15 0.3995 cscf.scu SipcMsgStatHandle
>> 14 0.3728 cscf.scu Urilex
>> 12 0.3196 cscf.scu DBFI_DATA_Search
>> 12 0.3196 cscf.scu SipDsmGetHdrBitValInner
>> 12 0.3196 cscf.scu SipSmGetDataFromRefString
>>
>> So, memcpy costs much more cpu cycles after live migration. Then, I
restart the process, this problem disappeared. save-restore has the
similar problem.
>>
>> perf report on vcpu thread in host,
>> pre live migration:
>> Performance counter stats for thread id '21082':
>>
>> 0 page-faults
>> 0 minor-faults
>> 0 major-faults
>> 31616 cs
>> 506 migrations
>> 0 alignment-faults
>> 0 emulation-faults
>> 5075957539 L1-dcache-loads
[21.32%]
>> 324685106 L1-dcache-load-misses # 6.40% of all
L1-dcache hits [21.85%]
>> 3681777120 L1-dcache-stores
[21.65%]
>> 65251823 L1-dcache-store-misses # 1.77%
[22.78%]
>> 0 L1-dcache-prefetches
[22.84%]
>> 0 L1-dcache-prefetch-misses
[22.32%]
>> 9321652613 L1-icache-loads
[22.60%]
>> 1353418869 L1-icache-load-misses # 14.52% of all
L1-icache hits [21.92%]
>> 169126969 LLC-loads
[21.87%]
>> 12583605 LLC-load-misses # 7.44% of all
LL-cache hits [ 5.84%]
>> 132853447 LLC-stores
[ 6.61%]
>> 10601171 LLC-store-misses #7.9%
[ 5.01%]
>> 25309497 LLC-prefetches #30%
[ 4.96%]
>> 7723198 LLC-prefetch-misses
[ 6.04%]
>> 4954075817 dTLB-loads
[11.56%]
>> 26753106 dTLB-load-misses # 0.54% of all dTLB
cache hits [16.80%]
>> 3553702874 dTLB-stores
[22.37%]
>> 4720313 dTLB-store-misses #0.13%
[21.46%]
>> <not counted> dTLB-prefetches
>> <not counted> dTLB-prefetch-misses
>>
>> 60.000920666 seconds time elapsed
>>
>> post live migration:
>> Performance counter stats for thread id '1579':
>>
>> 0 page-faults
[100.00%]
>> 0 minor-faults
[100.00%]
>> 0 major-faults
[100.00%]
>> 34979 cs
[100.00%]
>> 441 migrations
[100.00%]
>> 0 alignment-faults
[100.00%]
>> 0 emulation-faults
>> 6903585501 L1-dcache-loads
[22.06%]
>> 525939560 L1-dcache-load-misses # 7.62% of all
L1-dcache hits [21.97%]
>> 5042552685 L1-dcache-stores
[22.20%]
>> 94493742 L1-dcache-store-misses #1.8%
[22.06%]
>> 0 L1-dcache-prefetches
[22.39%]
>> 0 L1-dcache-prefetch-misses
[22.47%]
>> 13022953030 L1-icache-loads
[22.25%]
>> 1957161101 L1-icache-load-misses # 15.03% of all
L1-icache hits [22.47%]
>> 348479792 LLC-loads
[22.27%]
>> 80662778 LLC-load-misses # 23.15% of all
LL-cache hits [ 5.64%]
>> 198745620 LLC-stores
[ 5.63%]
>> 14236497 LLC-store-misses # 7.1%
[ 5.41%]
>> 20757435 LLC-prefetches
[ 5.42%]
>> 5361819 LLC-prefetch-misses # 25%
[ 5.69%]
>> 7235715124 dTLB-loads
[11.26%]
>> 49895163 dTLB-load-misses # 0.69% of all dTLB
cache hits [16.96%]
>> 5168276218 dTLB-stores
[22.44%]
>> 6765983 dTLB-store-misses #0.13%
[22.24%]
>> <not counted> dTLB-prefetches
>> <not counted> dTLB-prefetch-misses
>>
>> The "LLC-load-misses" went up by about 16%. Then, I restarted the
process in guest, the perf data back to normal,
>> Performance counter stats for thread id '1579':
>>
>> 0 page-faults
[100.00%]
>> 0 minor-faults
[100.00%]
>> 0 major-faults
[100.00%]
>> 30594 cs
[100.00%]
>> 327 migrations
[100.00%]
>> 0 alignment-faults
[100.00%]
>> 0 emulation-faults
>> 7707091948 L1-dcache-loads
[22.10%]
>> 559829176 L1-dcache-load-misses # 7.26% of all
L1-dcache hits [22.28%]
>> 5976654983 L1-dcache-stores
[23.22%]
>> 160436114 L1-dcache-store-misses
[22.80%]
>> 0 L1-dcache-prefetches
[22.51%]
>> 0 L1-dcache-prefetch-misses
[22.53%]
>> 13798415672 L1-icache-loads
[22.28%]
>> 2017724676 L1-icache-load-misses # 14.62% of all
L1-icache hits [22.49%]
>> 254598008 LLC-loads
[22.86%]
>> 16035378 LLC-load-misses # 6.30% of all
LL-cache hits [ 5.36%]
>> 307019606 LLC-stores
[ 5.60%]
>> 13665033 LLC-store-misses
[ 5.43%]
>> 17715554 LLC-prefetches
[ 5.57%]
>> 4187006 LLC-prefetch-misses
[ 5.44%]
>> 7811502895 dTLB-loads
[10.72%]
>> 40547330 dTLB-load-misses # 0.52% of all dTLB
cache hits [16.31%]
>> 6144202516 dTLB-stores
[21.58%]
>> 6313363 dTLB-store-misses
[21.91%]
>> <not counted> dTLB-prefetches
>> <not counted> dTLB-prefetch-misses
>>
>> 60.000812523 seconds time elapsed
>>
>> If EPT disabled, this problem gone.
>>
>> I suspect that kvm hypervisor has business with this problem.
>> Based on above suspect, I want to find the two adjacent versions of
kvm-kmod which triggers this problem or not (e.g. 2.6.39, 3.0-rc1),
>> and analyze the differences between this two versions, or apply the
patches between this two versions by bisection method, finally find the
key patches.
>>
>> Any better ideas?
>>
>> Thanks,
>> Zhang Haoyu
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