Messages in this thread | | | Date | Wed, 15 Apr 2009 08:57:39 +0800 | From | Li Zefan <> | Subject | Re: blktrace: event traces displayed wrong while ftrace blktrace is active |
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Theodore Tso wrote: > On Tue, Apr 14, 2009 at 11:25:33PM +0200, Frederic Weisbecker wrote: >> Indeed. Note that you can overwrite this default by typing: >> >> echo context-info > trace_option >> >> after setting bkltrace as the current tracer. > > The problem with doing that is that blktrace will then display this: > > fsync-tester-27934 [001] 208.031278: fsync-tester-27934 [001] 208.031278: 254,4 Q WS 268392 + 8 [fsync-tester] > > I think the real problem is that blk trace is displaying the standard > context-info, so it's suppressing the normal context info. So I have > the choice on having no context information on my event trace lines, > or two copies of the context information for the block trace lines. > > :-( >
I'll provide a patch to solve this confusing behavior.
> I'm guessing things were done this way in order to support the old > legancy blktrace format? >
Right, in 2 ways:
1. we can make the output the same as userspace 'btrace /dev/sda': # echo blk > current_tracer # echo 1 > options/blk_classic
2. we can make the binary output parsable by userspace blkparse: # echo blk > current_tracer # echo bin > trace_options # cat trace_pipe | blkparse -i -
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