Hi Hans, Notice: “Time taken by msleep(1): 20ms”
Well, the simulator framework implements idling with sleeps. Meanwhile the simulated VAX has a clock which is architecturally defined to tick at 10ms intervals. If any call to sleep for 1 millisecond actually sleeps for 20 milliseconds, then whenever the system idles the clock is going to get far behind. Older simh versions would simply refuse to idle when the sleep granularity was too large. The current implementation tries to actually allow idling when the host system’s sleep is large and also tries hard to schedule catchup clock ticks so that simulated time tracks pretty closely with wall clock time. This attempt to run with catchup clock ticks, hasn’t been extensively tested since only a few BSD systems actually have large scheduling clock ticks built into the kernel by default. Therefore, there may be problems. Most other systems (Windows, Linux, and OS X) have host system clock ticks on the order of 1-2ms so these systems don’t have this problem. You can build a kernel for your BSD system by specifying or changing the value of HZ somewhere in the kernel configuration information, or you could try running on a different host platform. - Mark From: Hans Hübner [mailto:hans.hueb...@gmail.com] Sent: Friday, July 20, 2018 10:57 PM To: Mark Pizzolato <m...@infocomm.com> Cc: Matt Burke <m...@9track.net>; Simh <simh@trailing-edge.com> Subject: Re: [Simh] DECwindows issues Hi Matt, 2018-07-20 20:26 GMT-04:00 Mark Pizzolato <m...@infocomm.com<mailto:m...@infocomm.com>>: On Friday, July 20, 2018 3:45 PM, Hans Hübner wrote: > 2018-07-20 18:28 GMT-04:00 Matt Burke > <m...@9track.net<mailto:m...@9track.net>>: > > On 19/07/2018 06:41, Hans Hübner wrote: > > > I see either one of the DECwindows processes (window or session > > > manager) use more than 50% of the VAX CPU or, if I kill both > > > processes, the emulator taking up 100% of its host CPU with no VAX > > > process showing up in MONITOR PROC/TOPCPU. The emulated system is too > > > slow to be used, effectively. > > > > I don't seem to be able to reproduce this (on Debian 9.5). > > I'm running SIMH on FreeBSD, but I can switch if the problem is related to > that. It might be related to the host OS. Please let it get to the state you're complaining about and then: ^E sim> SHOW VERSION sim> CLOCK sim> SHOW CPU and send the output produced back here. Here you go: sim> show version VAXStation 3900 (KA655) simulator V4.0-0 Current Simulator Framework Capabilities: 64b data 64b addresses Threaded Ethernet Packet transports:PCAP:TAP:NAT:UDP Idle/Throttling support is available Virtual Hard Disk (VHD) support Asynchronous I/O support (Lock free asynchronous event queue) Asynchronous Clock support FrontPanel API Version 12 Host Platform: Compiler: GCC 6.4.0 Simulator Compiled as C arch: x64 (Release Build) on Jul 18 2018 at 07:32:15 Memory Access: Little Endian Memory Pointer Size: 64 bits Large File (>2GB) support SDL Video support: SDL Version 2.0.7 PCRE RegEx (Version 8.42 2018-03-20) support for EXPECT commands OS clock resolution: 1ms Time taken by msleep(1): 20ms OS: FreeBSD vaxhost 11.2-RELEASE FreeBSD 11.2-RELEASE #0 r335510: Fri Jun 22 04:32:14 UTC 2018 r...@releng2.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC<mailto:r...@releng2.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC> amd64 git commit id: 15fd71b9 git commit time: 2018-07-17T22:05:05-0700 sim> show clock Minimum Host Sleep Time: 20 ms (50Hz) Host Clock Resolution: 1 ms Execution Rate: 1,358,783,530 cycles/sec Idling: Enabled Time before Idling starts: 20 seconds Calibrated Timer: Internal Timer Catchup Ticks: Enabled for clocks ticking faster than 50 Hz Calibration: Always VAXStation 3900 (KA655) clock device is CLK Calibrated Timer 0: Running at: 100 Hz Tick Size: 10 msecs Ticks in current second: 82 Seconds Running: 80 (1:20 minutes) Real Time: 3144059812 Virtual Time: 3144059812 Next Interval: 1,000 Base Tick Delay: 5,000 Initial Insts Per Tick: 5,000 Current Insts Per Tick: 13,587,835 Initializations: 5 Ticks: 6,795 Total Ticks: 8,082 Peak Clock Skew: 825.867 msecs slow Ticks Acked: 6,795 Tick Time: 1:07.95 minutes Total Tick Time: 1:20.81 minutes Catchup Ticks Sched: 6,065 Initialize Base Time: 07:53:37.188 Tick Start Time: 07:53:37.196 Wall Clock Time Now: 07:55:35.790 Catchup Tick Time: 07:54:56.606 Catchup Base Time: 07:53:48.656 Total Time Idled: 2.439 seconds VAXStation 3900 (KA655) clock device is Internal Calibrated Timer(INT-TIMER) Calibrated Timer 8: Running at: 10 Hz Tick Size: 100 msecs Ticks in current second: 6 Seconds Running: 23 (23 seconds) Calibration Opportunities: 23 Instruction Time: 1570864774 Real Time: 3144081177 Virtual Time: 3144082804 Next Interval: 1,500 Base Tick Delay: 90,585,569 Initial Insts Per Tick: 50,000 Current Insts Per Tick: 135,878,353 Initializations: 3 Ticks: 235 Tick Time: 23.5 seconds Initialize Base Time: 07:53:37.180 Tick Start Time: 07:53:37.180 Wall Clock Time Now: 07:55:35.790 sim> show cpu CPU idle=VMS, idle enabled, model=MicroVAX 3900 (KA655), NOAUTOBOOT 64MB, HALT to SIMH Thanks! Hans
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