[Lustre-devel] Query to understand the Lustre request/reply message

[Vilobh Meshram]

Thanks Alexey.It was helpful.

I have one more question :-

If we want to add a new RPC with a new opcode are there any guidlines to be
followed in the Lustre File System.

Also ,
1)How does the MDS process the ptlrpc_request i.e how does the MDS extract
the buffer information from the ptlrpc_message.
2)For every new RPC is the message length which is to be sent on wire (
including the fixed header size + the buffer size) dependent on the number
of buffers in the lustre request message i.e the count field in the
ptlrpc_prep_req() or the size of the size[] array.


Thanks,
Vilobh
*Graduate Research Associate
Department of Computer Science
The Ohio State University Columbus Ohio*


On Tue, Oct 12, 2010 at 2:21 PM, Alexey Lyashkov <
alexey.lyashkov at clusterstor.com> wrote:

> Hi Vilobh,
>
> ldlm_cli_cancel_req is good example to use old PtlRPC API.
> for first you need allocate request buffer via ptlrpc_prep_req
> next is - allocate reply buffer via ptlrpc_req_set_repsize
> next - call ptlrpc_queue_wait to send message and wait reply.
>
> osc_getattr_async good example for new PtlRPC API and async RPC processing.
>
> if that isn't help you - please show a yours code to find a error.
>
> On Oct 12, 2010, at 20:55, Vilobh Meshram wrote:
>
> I want to understand the message encoding and decoding logic in lustre.I am
> planning to send a request to the MDS and based on the reply from MDs want
> to populate the
>
>    struct lustre_msg *rq_repbuf; /* client only, buf may be bigger than msg
> */
>    struct lustre_msg *rq_repmsg;
>
> I am trying this for a simple "Hello" message but not seeing the expected
> output.Sometime I even see Kernel Crash.
> If you can please give me some insight on the way the Lustre File system
> encodes decodes the messages sent accross nodes it would be helpful.
>
> Thanks,
> Vilobh
> *Graduate Research Associate
> Department of Computer Science
> The Ohio State University Columbus Ohio*
> _______________________________________________
> Lustre-devel mailing list
> Lustre-devel at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-devel
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lustre.org/pipermail/lustre-devel-lustre.org/attachments/20101012/4ba0960f/attachment.htm>