[Linux-ia64] RT Timers problem

[Linux-ia64] RT Timers problem

[Steve Woodruff]

Hi - i've encountered a couple of different, but
maybe related problems in Debian linux on an RX2600
(ia64).  Maybe someone can comment if they've seen
this before?

1. RT signals RTMIN, RTMIN+1, RTMIN+2 are not being
   delivered.  I created a simple test case that sets
   an interval timer set to fire once per second, 
   but the signal never arrives!  When i use RTMIN+3
   or greater, then the code works fine.  I can 
   provide the test code to anyone who is interested
   in trying it out on their system.

2. In some cases, a call to timer_create() will block.
   This one is harder to reproduce, but i've done it
   multiple times and have something like this in 
   my code:

fprintf(stderr, 
  "HMM: Creating timer with signo=%d\n", 
  signal_no);
status =  timer_create(CLOCK_REALTIME,
  &h_event_struct, &h_timer_id);
fprintf(stderr, 
  "HMM: Timer created, status = %d\n", status);

And in the output, only the first line is
printed.  The timer_create() never returns!  I also
did a strace and the tail of that is:

write(2, "HMM: Creating timer with signo="..., 35HMM:
Creating timer with signo5
) = 35
getpid()                                = 591
getrlimit(RLIMIT_STACK, {rlim_curÅ92*1024,
rlim_max=RLIM_INFINITY}) = 0
brk(0)                                  0x600000000009c000
brk(0x60000000000a4000)                 0x60000000000a4000
pipe([2973872, 536870912])              = 4
SYS_1213(0x20000000000393a8, 0x60000000000988c0,
0x7fe0, 0xf00, 0x20000000002fc640, 0x20000000000393a8,
0x20000000002fc640, 0xf00) = 600
write(5, "\1\0\0\0\0\0\0\0\5\0\0\0\0\0\0\0pj-\0\0\0\0
\30\0\3\0\0"..., 168) = 168
rt_sigprocmask(SIG_SETMASK, NULL, [RT0], 8) = 0
write(5, "\200\300/\0\0\0\0
\0\0\0\0\0\0\0\0\10{\7\0\0\0\0 \10\257"..., 168) = 168
rt_sigprocmask(SIG_SETMASK, NULL, [RT0], 8) = 0
rt_sigsuspend([]

and there it sits.

Has anyone seen either of these problems come up
on debian linux/ia64? For what its worth, i was
using redhat AS back in January and the problems
never popped up back then, so i do think may be
specific to the librt provided in debian:
libc6.1-dev: /usr/lib/librt.so

Thanks,

/steve


==----------------------------------------------------------
 Steve Woodruff, N9OH @ 42.18N 88.34W, sjwoodr@yahoo.com

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Re: [Linux-ia64] RT Timers problem

[Matthew Wilcox]

On Wed, Apr 23, 2003 at 07:54:04AM -0700, Steve Woodruff wrote:
> 1. RT signals RTMIN, RTMIN+1, RTMIN+2 are not being
>    delivered.  I created a simple test case that sets
>    an interval timer set to fire once per second, 
>    but the signal never arrives!  When i use RTMIN+3
>    or greater, then the code works fine.  I can 
>    provide the test code to anyone who is interested
>    in trying it out on their system.

Aren't these used by libc for thread management purposes?  RH uses NPTL
so it ses different methods.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [Linux-ia64] RT Timers problem

[Steve Woodruff]

--- Matthew Wilcox <willy@debian.org> wrote:
> Aren't these used by libc for thread management
> purposes?  RH uses NPTL
> so it ses different methods.

Might be - i checked the libc6.1 docs and it
mentions that USR1 and USR2 were used for that
purpose, but then goes on to say that after 
kernel 2.1.60 that was no longer the case.  It
didn't mention, but perhaps its switched to
those first three RT sigs?

/steve



==----------------------------------------------------------
 Steve Woodruff, N9OH @ 42.18N 88.34W, sjwoodr@yahoo.com

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Re: [Linux-ia64] RT Timers problem

[Steve Woodruff]

> 2. In some cases, a call to timer_create() will
> block.
>    This one is harder to reproduce, but i've done it
>    multiple times and have something like this in 
>    my code:

Ok - i found the solution my self after some 
further research.  It appears that -lrt requires
-lpthread --even for non-threaded programs.  After
adding -pthread and explicitly listing -lpthread
before -lc in my link flags, all seems to be 
working as expected now.

tnx

/steve




==----------------------------------------------------------
 Steve Woodruff, N9OH @ 42.18N 88.34W, sjwoodr@yahoo.com

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