RELENG_10 performance regression (was Re: 35-40% performance drop releng9 vs releng10 openvpn

[Mike Tancsa]

On 3/21/2015 11:52 AM, John Baldwin wrote:

>> http://tancsa.com/time/
>
> Do you know why you are using the HPET instead of TSC for timestamping?

Hi,

I am not consciously making any time keep decisions.

kern.eventtimer.choice: HPET(550) HPET1(450) LAPIC(400) i8254(100) RTC(0)
kern.timecounter.choice: TSC(800) HPET(950) ACPI-fast(900) i8254(0) 
dummy(-1000000)

(The full hardware info is at the above url)


> Using the TSC can make a non-trivial performance difference since userland
> can calculate timestamps without using system calls when it is used.
> (That is not related to this case, but switching to the TSC in general is
> preferable.)
>
> There are a few generations of Intel CPUs where you can't mix deeper sleep
> states with the TSC as timecounter, but those CPUs are getting to be a bit
> older at this point.
>

This one is an AMD
CPU: AMD G-T40E Processor (1000.02-MHz K8-class CPU)
   Origin="AuthenticAMD"  Id=0x500f20  Family=0x14  Model=0x2  Stepping=0
 
Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT>
   Features2=0x802209<SSE3,MON,SSSE3,CX16,POPCNT>
   AMD Features=0x2e500800<SYSCALL,NX,MMX+,FFXSR,Page1GB,RDTSCP,LM>
   AMD 
Features2=0x35ff<LAHF,CMP,SVM,ExtAPIC,CR8,ABM,SSE4A,MAS,Prefetch,IBS,SKINIT,WDT>
   SVM: NP,NRIP,NAsids=8
   TSC: P-state invariant, performance statistics
real memory  = 2115297280 (2017 MB)
avail memory = 2018639872 (1925 MB)
Event timer "LAPIC" quality 400
ACPI APIC Table: <CORE   COREBOOT>
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
FreeBSD/SMP: 1 package(s) x 2 core(s)
  cpu0 (BSP): APIC ID:  0
  cpu1 (AP): APIC ID:  1
ioapic0 <Version 2.1> irqs 0-23 on motherboard
random: <Software, Yarrow> initialized
module_register_init: MOD_LOAD (vesa, 0xffffffff80d9ddf0, 0) error 19
kbd0 at kbdmux0
acpi0: <CORE COREBOOT> on motherboard
acpi0: Power Button (fixed)
cpu0: <ACPI CPU> on acpi0
cpu1: <ACPI CPU> on acpi0



-- 
-------------------
Mike Tancsa, tel +1 519 651 3400
Sentex Communications, mike at sentex.net
Providing Internet services since 1994 www.sentex.net
Cambridge, Ontario Canada   http://www.tancsa.com/