Re: TSC as timecounter makes system lag [-> jhb]

From: Larry Rosenman <ler_at_FreeBSD.org>
Date: Sun, 15 Jan 2017 11:02:38 -0600
On 2017-01-14 23:03, Julian Elischer wrote:
> On 15/01/2017 10:11 AM, Jia-Shiun Li wrote:
>> On Fri, Jan 13, 2017 at 8:26 AM, Jia-Shiun Li <jiashiun_at_gmail.com> 
>> wrote:
>> 
>>> Hi all,
>>> 
>>> since 2 or 3 weeks ago, I noticed that my old Penryn-based Intel 
>>> Pentium
>>> T4200 notebook lagged a lot. System time was running a lot slower,
>>> sometimes even looked like it freezed. Keystroke repeat rate was slow 
>>> too.
>>> 
>>> Since system time is slow, I tried to change timecounter from default 
>>> TSC
>>> to HPET. And it resumed normal immediately.
>>> 
>>> 
>> Did a binary search. Turns out it was caused by r310177 "Enable
>> EARLY_AP_STARTUP on amd64 and i386 kernels by default." r310175 does 
>> not
>> have this issue. Removing this option from kernel config also solves 
>> it.
> 
> making sure jhb notices this.
FWIW, I noted similar "slowness", and nooptions EARLY_AP_STARTUP makes 
it "normal"
again.

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FreeBSD 12.0-CURRENT #13 r311997: Sat Jan 14 22:35:29 CST 2017
     root_at_borg.lerctr.org:/usr/obj/usr/src/sys/VT-LER amd64
FreeBSD clang version 3.9.1 (tags/RELEASE_391/final 289601) (based on 
LLVM 3.9.1)
MEMGUARD DEBUGGING ALLOCATOR INITIALIZED:
         MEMGUARD map base: 0xfffffe0000400000
         MEMGUARD map size: 128600960 KBytes
VT(vga): resolution 640x480
CPU: Intel(R) Xeon(R) CPU           E5410  _at_ 2.33GHz (2327.55-MHz 
K8-class CPU)
   Origin="GenuineIntel"  Id=0x10676  Family=0x6  Model=0x17  Stepping=6
   
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
   
Features2=0xce3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,DCA,SSE4.1>
   AMD Features=0x20100800<SYSCALL,NX,LM>
   AMD Features2=0x1<LAHF>
   VT-x: HLT,PAUSE
   TSC: P-state invariant, performance statistics
real memory  = 68719476736 (65536 MB)
avail memory = 65353601024 (62326 MB)
Event timer "LAPIC" quality 100
ACPI APIC Table: <PTLTD          APIC  >
FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs


-- 
Larry Rosenman                     http://people.freebsd.org/~ler
Phone: +1 214-642-9640                 E-Mail: ler_at_FreeBSD.org
US Mail: 17716 Limpia Crk, Round Rock, TX 78664-7281
Received on Sun Jan 15 2017 - 16:02:39 UTC

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