Re: Time jumping on both 4.x and 5.x ...
From: Marc G. Fournier (scrappy_at_hub.org)
Date: 11/29/03
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Date: Sat, 29 Nov 2003 00:36:22 -0400 (AST) To: Kris Kennaway <kris@obsecurity.org>
On Fri, 28 Nov 2003, Kris Kennaway wrote:
> On Fri, Nov 28, 2003 at 09:32:30PM -0400, Marc G. Fournier wrote:
> >
> > In trying to isolate an issue where the PostgreSQL 'explain analyze' is
> > showing "odd results" (namely, negative time estimates on queries), Tom
> > Lane wrote a quick C program to test gettimeofday() (program attached) ...
> > the results on a 4.9-PRERELEASE kernel of Sep 20 14:16:48 ADT 2003 shows:
> >
> > neptune# time ./timetest
> > out of order tv_sec: 1070068479 99040, prev 1070069174 725235
> > out of order tv_usec: 1070068479 99040, prev 1070069174 725235
> > out of order tv_sec: 1070069175 19687, prev 1070068479 99040
> > out of order tv_usec: 1070069175 19687, prev 1070068479 99040
> > out of order tv_sec: 1070068499 99377, prev 1070069194 625573
> > out of order tv_usec: 1070068499 99377, prev 1070069194 625573
> > out of order tv_sec: 1070069194 808542, prev 1070068499 99377
> > ^C1.171u 23.461s 0:24.68 99.7% 5+169k 1+0io 0pf+0w
> >
> > One person on the list has tried the same script on a 5.2 kernel, and
> > reports seeing similar results, but after a longer period of time (~30min)
> > ...
>
> What hardware, kernel configuration, etc? Do you have a misconfigured
> ntpd/timed that is manually flapping the time around?
Hardware for the above is a Dual-Xeon, 4Gig of RAM, and about 421
processes running on it currently ... kernel config is at the bottom, but
I don't think there is anything 'abnormal' about it ... and note that I've
had others be able to reproduce the problem on both 4.x and 5.x systems
...
as to ntpd/timed ... don't run either ... run ntpdate twice a day (11:59
and 23:59), but that is it as far as playing with the clock is concerned
...
---- Marc G. Fournier Hub.Org Networking Services (http://www.hub.org) Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664 machine i386 cpu I686_CPU ident kernel maxusers 0 makeoptions DEBUG=-g #Build kernel with gdb(1) debug symbols options NMBCLUSTERS=16384 options VM_KMEM_SIZE="(400*1024*1024)" options VM_KMEM_SIZE_MAX="(400*1024*1024)" options NULLFS #NULL filesystem options UNION #Union filesystem options NFS #Network File System options COMPAT_LINUX options INET #InterNETworking options FFS #Berkeley Fast Filesystem options FFS_ROOT #FFS usable as root device [keep this!] options SOFTUPDATES #Enable FFS soft updates support options UFS_DIRHASH #Improve performance on big directories options PROCFS #Process filesystem options COMPAT_43 #Compatible with BSD 4.3 [KEEP THIS!] options SCSI_DELAY=15000 #Delay (in ms) before probing SCSI options KTRACE #ktrace(1) support options SYSVSHM options SHMMAXPGS=199608 options SHMMAX=(SHMMAXPGS*PAGE_SIZE+1) options SYSVSEM options SEMMNI=4096 options SEMMNS=8192 options SYSVMSG #SYSV-style message queues options P1003_1B #Posix P1003_1B real-time extensions options _KPOSIX_PRIORITY_SCHEDULING options ICMP_BANDLIM #Rate limit bad replies options KBD_INSTALL_CDEV # install a CDEV entry in /dev options SMP # Symmetric MultiProcessor Kernel options APIC_IO # Symmetric (APIC) I/O device isa device pci device ahd # AHA39320/29320 and onboard AIC79xx devices options AHD_REG_PRETTY_PRINT # Print register bitfields in debug # output. Adds ~215k to driver. device scbus # SCSI bus (required) device da # Direct Access (disks) device pass # Passthrough device (direct SCSI access) device ses device atkbdc0 at isa? port IO_KBD device atkbd0 at atkbdc? irq 1 flags 0x1 device psm0 at atkbdc? irq 12 device vga0 at isa? pseudo-device splash device sc0 at isa? flags 0x100 device npx0 at nexus? port IO_NPX irq 13 device em # Intel PRO/1000 adapter Gigabit Ethernet Card ( ``Wiseman'') pseudo-device loop # Network loopback pseudo-device ether # Ethernet support pseudo-device pty 256 # Pseudo-ttys (telnet etc) pseudo-device bpf #Berkeley packet filter options DDB options DDB_UNATTENDED options INCLUDE_CONFIG_FILE # Include this file in kernel _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
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