Re: BAST in RAC
- From: Mladen Gogala <mgogala@xxxxxxxxxxxxxxxxxxxx>
- To: kaygopal@xxxxxxxxx
- Date: Thu, 23 Dec 2004 14:24:36 -0500
K Gopalakrishnan wrote:
>In RAC the lock related operations are handled by Global Enqueue
>Services (GES) layer. Asynchronous System Traps (AST) are just like
>generic interrupt service routine. There are two types of interrupts
>or ASTs in the RAC. One is AAST (Acquisition AST) and another one is
>BAST (Blocking AST).This will be visible in the X$ structure X$LE
>(Lock Element?)
>
>When a process wants to acesss a resurce in RAC environment it needs
>to acquire lock and this will be given by GES. Before granting the
>lock to the process, GES will send the global AST to the holder of
>that resource and the
>holder may grant access to the requesting process. Once you have got
>the required locks on that resource GES will send an another AST
>(AAST) to tell that you have aqcuired the lock.
>
>GES will have the queue of requests/converts and will be delievering
>AST on an ongoing basis. BAST is the special kind of interrupt
>(Blocking AST) that will be sent to the process holding the resource
>that may lead some conflicts in the request conversions.
>
>
>
Aaaargh! I see that RDB gang has exercised some terminological influence
over the
rest of Oracle Corp. Those entities are NOT like interrupts. They're
implemented
through TCP control sockets and signals. Using the terminology from
another CPU
and another OS is confusing as hell. Somebody probably wanted to look
smart, so
they used those words without explanation or definition. If Oracle
picked RDB and
some terminology from the late DECosaurus Rex, it would be also nice to
pick a habit
of providing decent documentation as well. AST is something closely
related to
certain processor architecture and certain OS. Oracle is using those
terms, so that
people can pretend to be "experts". Whenever some oraclite mentions AST's in
my presence, I make sure that the experience isn't easily forgotten.
Your description of AST is what is scientifically known as mumbo-jumbo
(Oracle* Mumbo-Jumbo 10g) and makes no sense whatsoever. RAC processes work
over TCP sockets and do not "deliver interrupts". Processors and
hardware devices
deliver interrupts. Sockets deliver packets. If you want to provide
internal information,
please do it properly and not in a sloppy and misleading way using
incorrect and undefined terminology. This is the same comment that I've
sent in private email to Steve Adams when
he was talking about "ASTs" in his internals book.
--
Mladen Gogala
Oracle DBA
Ext. 121
--
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