Date: Wed, 8 Oct 2014 11:51:09 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Matt Fleming <matt@console-pimps.org>
Cc: Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Matt Fleming <matt.fleming@intel.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH 09/11] perf/x86/intel: Implement LRU monitoring ID
 allocation for CQM
Message-ID: <20141008095109.GD4750@worktop.programming.kicks-ass.net>
References: <1411567455-31264-1-git-send-email-matt@console-pimps.org>
 <1411567455-31264-10-git-send-email-matt@console-pimps.org>
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On Wed, Sep 24, 2014 at 03:04:13PM +0100, Matt Fleming wrote:
> From: Matt Fleming <matt.fleming@intel.com>
> 
> It's possible to run into issues with re-using unused monitoring IDs
> because there may be stale cachelines associated with that ID from a
> previous allocation. This can cause the LLC occupancy values to be
> inaccurate.
> 
> To attempt to mitigate this problem we place the IDs on a least recently
> used list, essentially a FIFO. The basic idea is that the longer the
> time period between ID re-use the lower the probability that stale
> cachelines exist in the cache.

Do we want to provide a user configurable minumum guaranteed queue time?
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