Re: 'Trace patches test' [Was: ccio_clear_io_tlb() and __raw_write() more question?]

[Grant Grundler <grundler@parisc-linux.org>]

On Tue, Jan 22, 2008 at 02:35:21PM +0100, rubisher wrote:
> Btw, a while back, I dream to use relayfs to grab debug info.
> (<http://lists.parisc-linux.org/pipermail/parisc-linux/2006-April/053237.html>)
> 
> Somebody else write it:
> <http://lkml.org/lkml/2007/11/13/208>
> 
> Obviously, I have to instrument things manually but I test it succesfully.
> Here is already some primarily data test:
> [snip]
> :1201001199222127606:ccio_map_single_1:ccio_map_single() 0x1eb91896 ->
> 0x63b4896 size: 0x1000
> :1201001199222203288:ccio_map_single_2: pdir 1fcb1da0 038100000eb91017
> :1201001199222391065:ccio_map_single_1:ccio_map_single() 0x1febc096 ->
> 0x63b5096 size: 0x1000
...
> Exciting results?

Yes! Nice!

> (just what would give me DEBUG_RUN() printk() but without
>  degrading system performance)

I don't believe that. :)
Measure the CPU utilization and/or compare pktgen performance with
and without the tracing compiled into the kernel.

However, that doesn't mean this is useless. This is alot better than
rolling our own "light weight" tracing mechanism and it's certainly
alot better than using printk's to debug DMA issues (as long as
the system doesn't crash - e.g. HPMC).

hth,
grant

> I still have to had some more DEBUG_RUN_SG() stuff and hope to be able to
> collect more.
> 
> Cheers,
>     r.
> 
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