Re: Async I/O question

Could the unknown297 call be for post/wait (postwait driver). As that is what is missing in the trace.

Anjo.

Diego Cutrone wrote:

> Hi list. Oracle 7.3.4.5IBM 4.3.3Raw devices based
> datafilesuse_async_io=TRUE While the database was processing some long
> update, I traced the LGWR proccess with SCTRACE utility (like truss in
> solaris or HP) and I got the following dump: LGWR
> proccess unknown297(0x1, 0x2ff0cfa8, 0x30, 0x2ff0cfa0, 0x2ff0ed00) ->
> 0
> times(0x2ff20fd8) -> 77507556 (0x49eabe4)
> 0x2ff20fd8:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> times(0x2ff21068) -> 77507556 (0x49eabe4)
> 0x2ff21068:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> times(0x2ff212c8) -> 77507556 (0x49eabe4)
> 0x2ff212c8:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> times(0x2ff212c8) -> 77507556 (0x49eabe4)
> 0x2ff212c8:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> times(0x2ff21018) -> 77507556 (0x49eabe4)
> 0x2ff21018:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> times(0x2ff21068) -> 77507556 (0x49eabe4)
> 0x2ff21068:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> unknown297(0x1, 0x2ff0cfa8, 0x3, 0x2ff0cfa0, 0x2ff0e058) -> 0
> times(0x2ff20fd8) -> 77507557 (0x49eabe5)
> 0x2ff20fd8:
> 0000: 00000015 000001e1 00000000 00000000 |................|
> times(0x2ff21068) -> 77507557 (0x49eabe5)
> 0x2ff21068:
> 0000: 00000015 000001e1 00000000 00000000 |................|and
> it keeps going..... I asume that unknown297() system call is the
> writting call here, as times() unknown297() and are the only calls
> that appearin the trace. After this testing I did the same trace in
> anOracle database 7.3.4.5File system based datafilesAIX 4.3.3 (same
> box)use_async_io = TRUE And I got the following output: LGWR
> proccess unknown297(0xa, 0, 0x4000982c, 0x1, 0x20034c78) -> -1
> EINTR(4) (Interrupted system call)
> times(0x2ff21438) -> 45035290 (0x2af2f1a)
> 0x2ff21438:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff215c8) -> 45035290 (0x2af2f1a)
> 0x2ff215c8:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> kwaitpid(0x2ff21520, -1, 0x5, 0x00000000) -> -1 ECHILD(10) (No child
> processes)
> kill(27736, SIG 0(0)) -> 0
> times(0x2ff215c8) -> 45035290 (0x2af2f1a)
> 0x2ff215c8:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21478) -> 45035290 (0x2af2f1a)
> 0x2ff21478:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> unknown297(0x12c, 0, 0x4000982c, 0x1, 0x20034c78)
> [unknown297] -> 0
> times(0x2ff21438) -> 45035477 (0x2af2fd5)
> 0x2ff21438:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21398) -> 45035477 (0x2af2fd5)
> 0x2ff21398:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21398) -> 45035477 (0x2af2fd5)
> 0x2ff21398:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff210e8) -> 45035477 (0x2af2fd5)
> 0x2ff210e8:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21138) -> 45035477 (0x2af2fd5)
> 0x2ff21138:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> kwrite(15, 0x4213be00, 55296) -> 55296 (0xd800)
> times(0x2ff210a8) -> 45035479 (0x2af2fd7)
> 0x2ff210a8:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21138) -> 45035479 (0x2af2fd7)
> 0x2ff21138:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> unknown297(0xa650, 0xc08, 0, 0x5, 0x420315b4) -> 0
> times(0x2ff21398) -> 45035479 (0x2af2fd7)
> 0x2ff21398:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21398) -> 45035479 (0x2af2fd7)
> 0x2ff21398:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff210e8) -> 45035479 (0x2af2fd7)
> 0x2ff210e8:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> times(0x2ff21138) -> 45035479 (0x2af2fd7)
> 0x2ff21138:
> 0000: 0000002d 00000175 00000000 00000000 |...-...u........|
> kwrite(15, 0x42149600, 59904) -> 59904 (0xea00)
> kwrite(15, 0x42130000, 48128) -> 48128 (0xbc00) As you can see
> kwrite, klseek, etc are used here.My questions are: Is unknown297
> system call related to KAIO system calls? Is kwrite related to
> Threaded Async I/O (the ones that uses the AIO servers) ? If I'm
> correct about what I've said before, I must assume that the unknown297
> system calls that I seein the second trace (FS based datafiles) are
> Oracle attemps to use KAIO (may be becauseuse_async_io is set to
> TRUE), and after these attemps have failed, Oracle uses kwritesystem
> call instead(Threaded Async I/O) Is this correct? If anyone can help,
> I'd greatly appreciate it. thanks in advanceGreetingsDC

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Author: Anjo Kolk
  INET: anjo_at_oraperf.com

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