Re: [Patch 0/3] driver data: blktrace pass-through

[Martin Peschke <mp3@de.ibm.com>]

On Wed, 2008-07-16 at 11:15 -0400, Alan D. Brunelle wrote:
> Martin Peschke wrote:
> > On Wed, 2008-07-16 at 10:47 -0400, Alan D. Brunelle wrote:
> >> Hm, again, if the blktrace | blkiomon (direct, no blkparse) is how you
> >> do things,
> > 
> > no, it's blktrace | blkparse | blkiomon
> > 
> > Isn't blkparse needed to sort all those per-CPU traces by time?
> > I want this feature.
> 
> The traces should come out pretty close from blktrace itself - I'm
> assuming you're interested in putting out statistics in multiples of
> seconds. Perhaps some test cases should be tried, but...

I will give it a try

> ... it certainly seems to me that if one could remove blkparse
> completely you'd save a /tremendous/ amount of CPU

sounds tempting to me

> at the slight cost of
> perhaps having some off-by-a-few counts. (Meaning: You may have a few
> C's that you could not match up with D's (because they come out "later"
> from blktrace).)

I had to make provisions for this case in blkiomon anyway.

I suspect blkparse's batch handling to deliver some C's earlier than the
matching D's. But I have never tracked it down.

Thanks,
Martin