linux-kernel - Re: [PATCH 12/12] perf kvm: add live mode

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Date:	Mon, 08 Oct 2012 14:54:10 -0600
From:	David Ahern <dsahern@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC:	linux-kernel@...r.kernel.org, mingo@...nel.org,
	peterz@...radead.org, fweisbec@...il.com,
	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>,
	Dong Hao <haodong@...ux.vnet.ibm.com>
Subject: Re: [PATCH 12/12] perf kvm: add live mode

On 10/8/12 2:35 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Oct 08, 2012 at 11:17:36AM -0600, David Ahern escreveu:
> Overall it looks good, I like the fact you're not doing it the way perf
> script does, i.e. that "pipe mode" thing, more or less like I'm doing on
> 'perf trace', but I think this is the time to get rid of 'perf_session'
> too for this specific "live mode" tools.

pipe mode would never work for this case. I'm looking at nested virt 
case now and it shows 360,000 events per second.

> I'm almost getting there for 'trace' and 'top', just need to move the
> ordered_samples code to evlist, then session, top, trace, kvm live and
> script will not need to use 'perf_session' at all.

ok. you going to have that soon?

> Also that 'perf_kvm__open_counters' really is just a third copy of code
> in 'record' and 'top', right? You could move it to
> 'perf_ev{list,open}__open' and solve this dup :-)

there's a TO-DO at the top of that function for that reason ;-) I copied 
a fair bit from perf-stat. Now that it's working I can look at code 
consolidation.

> I applied the cleanups/simple stuff, will try to do some of the prep
> work on ordered_samples to use on top and trace and then I think you
> could look there so that we get to something that is useful for all
> these !perf.data tools.

On my Westmere based server I am not seeing problems with timestamps and 
ordering (prior testing was on a Nehalem based server). It just 
weathered a 5 minute or so barrage of > 100,000 events per second 
(peaking at around 360k events/sec) with no problem.

David
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