Re: PHP performance on Xen domU with mulitple vcpu

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

On Fri, Apr 04, 2025 at 05:27:49PM -0700, Greg A. Woods wrote:
> So which Xen kernel version is this with?
> My bet is that it's newer than 4.11.

Indeed, this is 4.3.1

> Also which exact CPU model is your system using?

Quad intel Xeon:

cpu0: highest basic info 0000000d
cpu0: highest hypervisor info 40000005
cpu0: highest extended info 80000008
cpu0: Running on hypervisor: Xen
cpu0: "Intel(R) Xeon(R) CPU E3-1220 v6 @ 3.00GHz"
cpu0: Intel 7th or 8th gen Core (Kaby Lake, Coffee Lake) or Xeon E (Coffee Lake) (686-class)
cpu0: family 0x6 model 0x9e stepping 0x9 (id 0x906e9)
cpu0: features 0x1fc9cbf5<FPU,DE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MCA,CMOV,PAT>
cpu0: features 0x1fc9cbf5<CLFSH,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT>
cpu0: features1 0xc6d82203<SSE3,PCLMULQDQ,SSSE3,CX16,SSE41,SSE42,MOVBE,POPCNT>
cpu0: features1 0xc6d82203<AES,XSAVE,RDRAND,RAZ>
cpu0: features2 0x28100800<SYSCALL/SYSRET,XD,RDTSCP,EM64T>
cpu0: features3 0x121<LAHF,LZCNT,PREFETCHW>
cpu0: features5 0x8c2b09<FSGSBASE,BMI1,BMI2,ERMS,RTM,FPUCSDS,RDSEED,ADX>
cpu0: features5 0x8c2b09<CLFLUSHOPT>
cpu0: features7 0x20000000<ARCH_CAP>
cpu0: xsave features 0x3<x87,SSE>
cpu0: xsave instructions 0x7<XSAVEOPT,XSAVEC,XGETBV>
cpu0: xsave area size: current 576, maximum 576, xgetbv disabled
cpu0: I-cache: 32KB 64B/line 8-way, D-cache: 32KB 64B/line 8-way
cpu0: L2 cache: 256KB 64B/line 4-way
cpu0: L3 cache: 8MB 64B/line 16-way
cpu0: 64B prefetching
cpu0: ITLB: 128 4KB entries 8-way, 8 2M/4M entries
cpu0: DTLB: 64 4KB entries 4-way, 4 1GB entries 4-way
cpu0: L2 STLB: 1536 4KB entries 6-way
cpu0: Initial APIC ID 0
cpu0: Cluster/Package ID 0
cpu0: Core ID 0
cpu0: SMT ID 0
cpu0: monitor-line size 0
cpu0: SEF highest subleaf 00000000
cpu0: Power Management features: 0x100<ITSC>
cpu0: Perfmon: Ver. 0
cpu0: Perfmon: General: bitwidth 0, 0 counters
cpu0: microcode version 0xf8, platform ID 1

> It is interesting that setting kern.timecounter.hardware=clockinterrupt
> is enough to work around the ntpd problem -- I'll try that for the
> similar problems I've been having with Xen kernels >= 4.18.

Well, no, it happens with clockinterrupt, not with xen_system_time.
But with xen_system_time, ntpd is unable to keep in sync.


-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost