[Lustre-discuss] Printing the data in OST code

Jack David jd6589 at gmail.com
Tue Feb 21 06:44:26 PST 2012

On Tue, Feb 21, 2012 at 8:13 PM, Jack David <jd6589 at gmail.com> wrote:
> Hi All,
> I am trying to analyze the OSC-OST communication by putting some
> prints in the code. Basically I want to print the data that is sent by
> OSC and received by OST. But I am not able to print the correct, may
> be because of I am not printing the correct buffers. Please correct me
> in the following approach which I have taken.
> On the OST side, whenever the OST_WRITE request comes, following code
> path is taken
> ost_brw_write()
> -- target_bulk_io()
> -- -- ptlrpc_start_bulk_transfer()
> -- -- -- LNetGet()
> In the ptlrpc_start_bulk_transfer(), the "desc" parameter contains the
> pages and that is filled into the "MD". I assume if I print those
> pages at this point (before calling LNetGet()), I will not get the
> data.
> Once the LNetGet() is called, the GET request will be served by lower
> layer and lnet_finalize() will be invoked as a call back routine to
> notify that the operation is complete. In "lnet_finalize()", I am
> filtering the "msg" (passed in as parameter) with type LNET_MSG_GET to
> pin point the correct "msg". This struct "msg" will contain the
> "lnet_libmd_t" type of MD which will have the kiov as well as "start"
> buffer. If I print that buffer, still the data is garbage.
> I would appreciate any help on this issue.
> Thanks,
> J

Forgot to mention that Lustre MDS, OSS and Lustre Client are on the
same machine.


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