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Re: Where stap spends its time producing instrumentation for testsuite/systemtap.syscall/sys.stp


wcohen wrote:

> [...] Below is the the experiment to see how long it takes to build the
> [systemtap.syscall/sys.stp] instrumentation with oprofile collecting
> data. 

Thanks.

> The analysis pass (pass 2) and compilation pass take a over 30
> seconds each.

Yeah, that's far too long.

> Pass 1: parsed user script and 37 library script(s) in 530usr/20sys/626real ms.
> Pass 2: analyzed script: 768 probe(s), 108 function(s), 14 embed(s), 4
> global(s) in 39690usr/360sys/40385real ms.

This part is likely to improve with the better elfutils-dwfl caching
widget I'm working on for the user-space probing support.

> Pass 3: translated to C into "/tmp/stapnoy9IG/xyz.c" in 300usr/110sys/462real ms.
> Pass 4: compiled C into "xyz.ko" in 34080usr/1500sys/36972real ms. [...]
> $ wc /tmp/stapnoy9IG/xyz.c
>  120522  352489 4295506 /tmp/stapnoy9IG/xyz.c
> $ size /tmp/stapnoy9IG/xyz.ko
>    text    data     bss     dec     hex filename
> 1134094  169408    4816 1308318  13f69e /tmp/stapnoy9IG/xyz.ko

Both compilation time & result size numbers will have improved greatly
since the time you took these measurements due to some code generation
improvements (see bug #5096 and #5102).

There is a chance that future implementation of bug #5075 could create
many more code elision opportunities as $argstr computation is moved
out of explicit script code.


- FChE


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