Messages in this thread | | | Date | Sat, 29 Apr 2006 00:05:59 +0530 | From | Balbir Singh <> | Subject | Re: [Lse-tech] Re: [Patch 5/8] taskstats interface |
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> >Is this what you had in mind? > > > No exactly. The payload information must be always available for > application. > > On a second thought, the idea of one big taskstats struct with many > #ifconfig is not really a good idea. My goal is to cut down unnecessary > data being transfered throught the socket.
Yes, so we agree that #ifdef CONFIG_* is not good.
> > Here is my Take 2. We can have a taskstats header containing taskstats > version and other general fields useful to more than one taskstats > application including a payload information. Then, we define > accounting subsystem specific structs for delayacct, csa, etc. > The kernel/{delayacct.c,csa.c,etc.c} set the payload information and > fill the buffer with desired subsystem structs. The header thus contain > enough information to tell applications how to map the data following > the header.
I agree with this suggestion.
Each netlink attribute contains the following fields (also referred to as TLV)
+----+--------+------+ |Type| length | value| +----+--------+------+
The type is meant to serve the purpose of the header you describe. The type value can be used by the application to map the data. getdelays.c is a sample application posted in the previous patches, it interprets data based on type.
> > Would IBM propose more accounting subsystems besides delayacct? > If we only see delayacct and csa on the horizon, this scheme is really > not necessary since delayacct does not have as much data (as csa :)) > and csa can use part of the delayacct data. You gain more than > csa can benefit from this. ;-) I guess i just speak from design point > of view. :) > > But, if one day somebody who does not need a paycheck decides > to convert BSD accounting to use taskstats interface, this can > be helpful. >
Yes, I think in the long term it would be more useful to use the scheme of adding subsystem structs. taskstats.txt explains the process of extending taskstats. Point #2 is the same as what we have just discussed. Could you please see if the text needs any changes based on our discussions so far (taskstats.txt was posted in the delayacct-doc.patch).
> Thanks, > - jay > >
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