Hi Devon,
I think now that we the ability to define exactly which metrics should and
should not be summarised then the issue of slow-downs due to metric
summarisation can be managed.
If we are to look at redoing the XML parsing next then the two contenders
that come to mind are gzipped JSON and Google Protocol Buffers.
PB is meant to be very efficient and therefore faster, however it seems
people have gotten comparable results with gzipped JSON. An obvious
advantage of gzipped JSON is that it would be simple to make the output
human readable though we could easily develop a CLI tool that allowed us to
query and decode ganglia PB data for testing.
What do others think?
--Nick.
On Tue, Jan 14, 2014 at 4:42 PM, Devon H. O'Dell <devon.od...@gmail.com>wrote:
> I don't personally have any objections, but if this remains a pain
> point, perhaps this is something we can address differently? I think
> where I left off, XML parsing was the taking the most time; is that
> something that people are comfortable with changing (data format?)
>
> --dho
>
> 2014/1/14 Nicholas Satterly <nfsatte...@gmail.com>:
> > Given the performance benefits gained by Devon's work I will revert the
> > patch that attempted to speed up metric summaries because it's causing
> > grid-of-grids to fail (unless there are any objections) ...
> >
> >
> https://github.com/ganglia/monitor-core/commit/0705a5defa284e289004daf61ea390338719d5fb
> >
> > --Nick.
> >
> >
> > On Tue, Dec 10, 2013 at 8:00 PM, Chris Burroughs <
> chris.burrou...@gmail.com>
> > wrote:
> >>
> >> On 12/08/2013 04:43 PM, Devon H. O'Dell wrote:
> >> >> This is a simple `perf top -p $PID` on one of of our gmetad nodes
> >> >> >
> >> >> >Samples: 1M of event 'cycles', Event count (approx.): 64115959770
> >> >> > 6.59% libexpat.so.1.5.2 [.] 0x0000000000011b8d
> >> >> > 4.77% libganglia-3.6.0.so.0.0.0 [.] hashval
> >> >> > 2.62% [kernel] [k] __d_lookup
> >> >> > 2.21% [kernel] [k] _spin_lock
> >> >> > 2.14% libc-2.12.so [.] vfprintf
> >> >> > 1.61% librrd.so.4.2.0 [.] process_arg
> >> >> > 1.54% libganglia-3.6.0.so.0.0.0 [.] hash_lookup
> >> >> > 1.46% [kernel] [k] __link_path_walk
> >> >> > 1.16% libc-2.12.so [.] __GI_____strtod_l_internal
> >> >> > 1.11% libc-2.12.so [.] memcpy
> >> >> > 1.08% libc-2.12.so [.] _int_malloc
> >> >> >
> >> >> >So I suppose my intuition about xml parsing expense is off. I have
> >> >> > not used
> >> >> >perf as much as I should, if we were seeing similar rrd writing
> >> >> > contention
> >> >> >should I literally see "stat" near the top?
> >> > Ah, so to see what's really going on:
> >> >
> >> > perf record -e cpu-clock -g -p $PID
> >> >
> >> > Let that run for a minute or two. Then:
> >> >
> >> > perf report --sort=comm,dso,symbol -G
> >> >
> >> > If you don't have cpu-clock, cycles is OK, but you definitely are
> >> > going to want to see the callgraph. The time in XML is mostly writing
> >> > RRDs and you only see that digging down into the chain.
> >> >
> >>
> >>
> >> For the list, Devon and I spoke in #ganglia and the high occurrence of
> >> libexpat in this sample seems to be an artifact of missing debug
> symbols.
> >>
> >>
> >>
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> >> _______________________________________________
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> >> Ganglia-developers@lists.sourceforge.net
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> >
> >
> >
> >
> > --
> > gpg: using PGP trust model
> > pub 4096R/1EE38BD9 2013-01-06 [expires: 2018-01-06]
> > Key fingerprint = 3EE9 550D D9D8 DB65 58C2 B58D CE78 EC6C 1EE3
> 8BD9
> > uid Nicholas Satterly (Debian Key) <
> nfsatte...@gmail.com>
> > sub 4096R/23804EE9 2013-01-06 [expires: 2018-01-06]
> >
>
--
gpg: using PGP trust model
pub 4096R/1EE38BD9 2013-01-06 [expires: 2018-01-06]
Key fingerprint = 3EE9 550D D9D8 DB65 58C2 B58D CE78 EC6C 1EE3 8BD9
uid Nicholas Satterly (Debian Key) <nfsatte...@gmail.com>
sub 4096R/23804EE9 2013-01-06 [expires: 2018-01-06]
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