gettimeofday is a "fast trap system call" (T_FASTTRAP). The kernel
does not save all the state (registers, for example) that a normal
system call entry point performs. And I believe the kernel entry point
for fast trap system calls does not trigger the DTrace probe.
The reason why you see gettimeofday() in pstack is because it
gettimeofday() is still a proper function, which has the stack frame
and other context information for pstack to recognize it when looking
at the process' stack frame.
Rayson
P.S. Anatoli, you are in the Toronto office? Please send my greetings
to Prof Stumm!
On 10/8/08, Anatoli <[EMAIL PROTECTED]> wrote:
> Hi, All
> Below is some data and a questions is 'why I do not see gettimeofday with
> truss & dtrace, but pstack' ?
> (NOTE: I am on the global container, not in zone)
>
> PS: when running, gettimeofday consumes whole CPU
>
> 1) # uname -a
> SunOS *** 5.10 Generic_127112-11 i86pc i386 i86pc Solaris
> 2) # cat gettimeofday.c
> #include <sys/time.h>
>
> int main( int argc, char* argv[] ){
> struct timeval tv;
>
> while( 1 )
> gettimeofday( &tv, 0 );
> }
> 3) # gcc -g -O0 -o gettimeofday gettimeofday.c
> 4) # date ; truss ./gettimeofday ; date
> Wednesday, October 8, 2008 12:31:17 PM EDT
> execve("gettimeofday", 0x08047CD0, 0x08047CD8) argc = 1
> resolvepath("/usr/lib/ld.so.1", "/lib/ld.so.1", 1023) = 12
> getcwd("/root/DT-astanko", 1010) = 0
> resolvepath("/root/DT-astanko/gettimeofday", "/root/DT-astanko/gettimeofday",
> 1023) = 29
> sysconfig(_CONFIG_PAGESIZE) = 4096
> xstat(2, "/root/DT-astanko/gettimeofday", 0x08047AA8) = 0
> open("/var/ld/ld.config", O_RDONLY) = 3
> fxstat(2, 3, 0x080479E8) = 0
> mmap(0x00000000, 140, PROT_READ, MAP_SHARED, 3, 0) = 0xFEFC0000
> close(3) = 0
> mmap(0x00000000, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON,
> -1, 0) = 0xFEFB0000
> xstat(2, "/lib/libc.so.1", 0x080472D8) = 0
> resolvepath("/lib/libc.so.1", "/lib/libc.so.1", 1023) = 14
> open("/lib/libc.so.1", O_RDONLY) = 3
> mmap(0x00010000, 32768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_ALIGN, 3, 0) =
> 0xFEFA0000
> mmap(0x00010000, 876544, PROT_NONE,
> MAP_PRIVATE|MAP_NORESERVE|MAP_ANON|MAP_ALIGN, -1, 0) = 0xFEEC0000
> mmap(0xFEEC0000, 772077, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_TEXT,
> 3, 0) = 0xFEEC0000
> mmap(0xFEF8D000, 27239, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED|MAP_INITDATA, 3, 774144) = 0xFEF8D000
> mmap(0xFEF94000, 5392, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANON,
> -1, 0) = 0xFEF94000
> munmap(0xFEF7D000, 65536) = 0
> memcntl(0xFEEC0000, 123384, MC_ADVISE, MADV_WILLNEED, 0, 0) = 0
> close(3) = 0
> mmap(0x00010000, 24576, PROT_READ|PROT_WRITE|PROT_EXEC,
> MAP_PRIVATE|MAP_ANON|MAP_ALIGN, -1, 0) = 0xFEEB0000
> munmap(0xFEFA0000, 32768) = 0
> getcontext(0x08047860)
> getrlimit(RLIMIT_STACK, 0x08047858) = 0
> getpid() = 18738 [18737]
> lwp_private(0, 1, 0xFEEB2A00) = 0x000001C3
> setustack(0xFEEB2A60)
> sysi86(SI86FPSTART, 0xFEF94BC0, 0x0000133F, 0x00001F80) = 0x00000001
> ^C Received signal #2, SIGINT [default]
> Wednesday, October 8, 2008 12:31:26 PM EDT
> 5) # dtrace -l | grep gettimeofday
> 13691 fbt genunix gettimeofday entry
> 13692 fbt genunix gettimeofday return
> 47531 syscall gettimeofday entry
> 47532 syscall gettimeofday return
> 6) # date ; dtrace -vn
> 'syscall::gettimeofday:entry{trace("gettimeofday:entry");}' ; date
> Wednesday, October 8, 2008 12:36:23 PM EDT
> dtrace: description 'syscall::gettimeofday:entry' matched 1 probe
>
> Stability attributes for description syscall::gettimeofday:entry:
>
> Minimum Probe Description Attributes
> Identifier Names: Private
> Data Semantics: Private
> Dependency Class: ISA
>
> Minimum Statement Attributes
> Identifier Names: Stable
> Data Semantics: Stable
> Dependency Class: Common
>
> ^C
>
> Wednesday, October 8, 2008 12:36:30 PM EDT
> 7) # pstack `pgrep gettimeofday`
> 19500: ./gettimeofday
> fef65137 gettimeofday (80506f0, 1, 8047cd0) + 7
> 080506f0 _start (1, 8047da4, 0, 8047db3, 8047df4, 8047e0c) + 80
> --
> This message posted from opensolaris.org
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