On Fri, 2006-11-17 at 12:09 -0500, Ming Zhang wrote:
> > > i have another question. for example, each events are marked with
> a
> > > sequence number in blkparse output. but that number is not useful.
> i did
> > > not ready source code yet, but i believe there is internal
> connection
> > > for each event. for example, request X Q in event M, D in even N,
> C in
> > > event Z... So if output of blkparse can print out such info, then
> we
> > > have a complete chain to go from Q2C for each request
> individually.
> > >   
> > This could be added - but in some instances there is a lot of data.
> Let 
> > me take a quick look into it.
> 
> if this is the core data structure
> http://lxr.linux.no/source/include/linux/blktrace_api.h?v=2.6.18#L76,
> will a u32 parent_sequence will enable this feature?
> 
> 

have a quick code read, seems that hard to get the parent_sequence value
unless we add another field in bio structure and keep updating it.

ps, __blk_add_trace()
http://lxr.linux.no/source/block/blktrace.c?v=2.6.18#L89 take so many
parameters that lead to high function call overhead. i know it wants to
be generic for all cases. but can we have a fast function for the most
frequent path?

Ming


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