Date: Sat, 7 Oct 2000 00:13:36 +0300 From: Valentin Nechayev <netch@netch.kiev.ua> To: freebsd-current@freebsd.org, phk@freebsd.org Subject: microuptime() went backwards: possible diagnosis Message-ID: <20001007001336.A346@nn.kiev.ua>
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Following is partial dmesg output from 5.0(13)-CURRENT-20001002 kernel
with advanced debugging prints:
==={{{
mi_startup(): call subsystem 0x8800000(142606336), microuptime is 1.4027506
mi_startup(): call subsystem 0x8800000(142606336), microuptime is 1.4027897
mi_startup(): call subsystem 0xa000000(167772160), microuptime is 1.4028290
mi_startup(): call subsystem 0xa800000(176160768), microuptime is 1.4028701
mi_switch(): microuptime() went backwards (1.4029032 -> 0.734106)
mi_switch(): microuptime() went backwards (1.4029032 -> 0.734590)
mi_switch(): microuptime() went backwards (1.4029032 -> 0.735077)
mi_switch(): microuptime() went backwards (1.4029032 -> 0.735555)
[...]
mi_switch(): microuptime() went backwards (1.4029032 -> 1.053263)
mi_switch(): microuptime() went backwards (1.4029032 -> 1.053756)
mi_startup(): call subsystem 0xd000000(218103808), microuptime is 1.054550
proc0_post(): switchtime initialized to 1.54864
mi_startup(): call subsystem 0xe000000(234881024), microuptime is 1.055501
mi_startup(): call subsystem 0xe400000(239075328), microuptime is 1.056012
===}}}
mi_switch() uses static variable 'switchtime' which keeps microuptime
data when previous switching occured. For non-MP systems, proc0_post()
sets it up. But first mi_switch() call occures when SI_SUB_INT_CONFIG_HOOKS
(or SI_SUB_KICK_SCHEDULER?) subsystem called - why? IMHO it is too early
for mi_switch(), it should be enabled on SI_SUB_RUN_SCHEDULER.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
This was first question. Another one is strange value returned by
microuptime() (3-5 millions of microseconds). This value becomes strange
on my system during third SI_SUB_CONFIGURE instance, which is configure()
in i386/i386/autoconf.c:
[...]
isa_probe_children: before probing non-PNP device: microuptime=0.349777, x=0
fdc0: <NEC 72065B or clone> at port 0x3f0-0x3f5,0x3f7 irq 6 drq 2 on isa0
fdc0: FIFO enabled, 8 bytes threshold
fd.c: fd_probe(): before set_motor(): microuptime=0.291463, x=0
fdc0: FIFO enabled, 8 bytes threshold
fd.c: fd_probe(): before NE7CMD_SENSED(): microuptime=1.292409, x=0
fd0: <1440-KB 3.5" drive> on fdc0 drive 0
isa_probe_children: after probing non-PNP device: microuptime=1.1653283, x=0
isa_probe_children: before probing non-PNP device: microuptime=1.1604514, x=7
atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
kbd0 at atkbd0
isa_probe_children: after probing non-PNP device: microuptime=1.3138749, x=7
[...]
it isn't possible to normalize value during this subsystem startup, is it?
/netch
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