Re: [libvirt] Is it a workqueue related issue in 2.6.37 (Was: Re: blkio cgroup [solved])
On Fri, 2011-02-25 at 15:18 -0500, Vivek Goyal wrote:
Thanks Steve. In this case this feature of sending trace data over
network would have helped. We were running into issues where IO scheduler
was freezing so we could not read anything from disk(including saved traces).
Hence we were directing everything to console and then doing copy paste.
So sending it over network would have probably worked even in this case.
Will give trace-cmd a try next time.
Hi Vivek,
I just pushed out a hack that lets trace-cmd read the blktrace.
I found that the blktrace never exported its structure to
the /debug/tracing/events/ftrace/blktrace/format. So userspace has no
real way to know how to parse it.
Instead, I wrote a hack that creates this file semi dynamically, based
on the information of other events. I also copied a lot of the blktrace
code from the kernel so that it can print out the same format.
You need to install the plugin that is built with trace-cmd. It will
either be automatically installed if you do a make install, but if you
do not have root access, just cp the plugin_blk.so into
~/.trace-cmd/plugins directory (you may need to make that directory
yourself). Then when you run trace-cmd report on a file made with the
blk tracer, it will give you a nice output.
If you already have a trace.dat file from a previous extract, you don't
need to run the trace again. The trace-cmd report will work on that file
now.
I'll be heading out to NYC on Monday for the End Users Conf and this
weekend I need to get all my chores done around the house for the misses
to let me go ;) Thus, I wont be doing much more till I get back at the
end of next week.
-- Steve