From: Matt Fleming <matt@console-pimps.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Andi Kleen <andi@firstfloor.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Kanaka Juvva <kanaka.d.juvva@intel.com>,
Matt Fleming <matt.fleming@intel.com>
Subject: Re: [PATCH v4 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs
Date: Sun, 11 Jan 2015 10:45:51 +0000 [thread overview]
Message-ID: <20150111104551.GA30245@codeblueprint.co.uk> (raw)
In-Reply-To: <20150109125829.GF29390@twins.programming.kicks-ass.net>
On Fri, 09 Jan, at 01:58:29PM, Peter Zijlstra wrote:
>
> Right, but we'll also consider RMIDs with less than this as fit for
> reuse. So we'll re-use RMIDs that are effectively full.
>
> Our aim is to acquire an 'empty' RMID, not give up and start reusing
> full ones just because, right?
The threshold was designed so that we're guaranteed to make forward
progress. If we're bumping the threshold, *none* of the RMIDs on the
limbo list have an occupancy value less than the threshold value.
At that point, we've got two options,
1) Increase the threshold value and further skew the results
2) Steal another RMID and pray it's below the threshold
We actually do both currently.
Now, one thing that we don't do is traverse the entire list of active
RMIDs looking for the least value one, because it's pretty expensive to
do that as it incurs lots of MSR reads and writes.
--
Matt Fleming, Intel Open Source Technology Center
next prev parent reply other threads:[~2015-01-11 10:45 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-14 21:15 [PATCH v4 00/11] perf: Intel Cache QoS Monitoring support Matt Fleming
2014-11-14 21:15 ` [PATCH 01/11] perf tools: Parse event per-package info files Matt Fleming
2014-11-14 21:15 ` [PATCH 02/11] perf tools: Implement snapshot event file logic Matt Fleming
2014-11-14 21:15 ` [PATCH 03/11] perf: Make perf_cgroup_from_task() global Matt Fleming
2014-11-14 21:15 ` [PATCH 04/11] perf: Add ->count() function to read per-package counters Matt Fleming
2014-11-14 21:15 ` [PATCH 05/11] perf: Move cgroup init before PMU ->event_init() Matt Fleming
2014-11-14 21:15 ` [PATCH 06/11] x86: Add support for Intel Cache QoS Monitoring (CQM) detection Matt Fleming
2014-11-14 21:15 ` [PATCH 07/11] perf/x86/intel: Add Intel Cache QoS Monitoring support Matt Fleming
2014-11-14 21:15 ` [PATCH 08/11] perf/x86/intel: Implement LRU monitoring ID allocation for CQM Matt Fleming
2014-11-14 21:15 ` [PATCH v4 09/11] perf/x86/intel: Support task events with Intel CQM Matt Fleming
2014-11-14 21:15 ` [PATCH v4 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs Matt Fleming
2015-01-06 16:13 ` Peter Zijlstra
2015-01-06 17:17 ` Peter Zijlstra
2015-01-09 12:14 ` Matt Fleming
2015-01-09 13:02 ` Peter Zijlstra
2015-01-09 15:24 ` Matt Fleming
2015-01-09 15:58 ` Peter Zijlstra
2015-01-15 15:31 ` Matt Fleming
2015-01-15 19:37 ` Matt Fleming
2015-01-06 17:36 ` Peter Zijlstra
2015-01-09 12:22 ` Matt Fleming
2015-01-09 12:59 ` Peter Zijlstra
2015-01-07 12:16 ` Peter Zijlstra
2015-01-09 12:55 ` Matt Fleming
2015-01-09 12:58 ` Peter Zijlstra
2015-01-11 10:45 ` Matt Fleming [this message]
2014-11-14 21:15 ` [PATCH 11/11] perf/x86/intel: Enable conflicting event scheduling for CQM Matt Fleming
2015-01-08 11:49 ` Peter Zijlstra
2015-01-09 12:56 ` Matt Fleming
2015-01-08 11:51 ` Peter Zijlstra
2015-01-09 14:27 ` Matt Fleming
2014-11-25 14:55 ` [PATCH v4 00/11] perf: Intel Cache QoS Monitoring support Matt Fleming
2014-12-18 7:59 ` Matt Fleming
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