Re: variables in scopes

[Richard J Moore <richardj_moore at uk dot ibm dot com>]

Vara Prasad wrote on 14/04/2005 14:57:32:


> I think if we go the route of full "C" syntax we will not be any where
> close to what Dtrace offers in the area of ease of use. The most value i
> see in SystemTAP is knowledge of experts provided in the form of
> tapsets. The role of the language is an easy way to access those tapsets
> and data they provide. Once we develop decent set of tapset libraries
> most people including kernel developers for most of the common tasks
> find what is available in the library sufficient.  There might be
> occasions where one needs more than what is available and if you are a
> kernel developer you can always edit generated code and add what you
> need and make the module. If you are an end user even if the language
> allows without considerable kernel knowledge you wont be able to enhance
> the library anyway so it doesn't matter.
>
> I would like to point out that recently in a customer situation some of
> the best Linux Kernel experts who have developed entire filesystems and
> major parts of the vm area etc. were trying to solve a performance
> problem along side the Sun folks. Sun folks using the Dtrace were able
> to narrow down the problem literally in less than 30 minutes and  Linux
> Kernel  folks couldn't figure out even for days.  These guys are Kernel
> experts, their main feedback to me was your Kprobe stuff is cool but not
> very useful without library that exports the data and a simple scripting
> language. I think we should not forget that language role is to make it
> easy to get what we want out of kernel. If we make this as a full blown
> c language, then i see where little difference in writing systemtap
> scripts vs kprobe modules.
>
> Just my 2 cents.
>
> bye,
> Vara Prasad
>


Agreed. If one wants the write probes in C then why use an interpretive
form of C?
Surely one would write kernel modules that would call the kprobes KPIs
directly.