From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
eranian@google.com, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 3/3] perf, x86: Add INST_RETIRED.PREC_DIST workarounds
Date: Wed, 13 Aug 2014 10:10:17 +0200 [thread overview]
Message-ID: <20140813081017.GA9918@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1407894315-15928-3-git-send-email-andi@firstfloor.org>
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On Tue, Aug 12, 2014 at 06:45:15PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> On Broadwell INST_RETIRED.PREC_DIST cannot be used with any period
> that doesn't have the lowest 6 bits cleared. And the period
> should not be smaller than 128.
>
> Add a new callback to enforce this, and set it for Broadwell.
>
> This is erratum BDM57 and BDM11.
Urgh, this blows.
> +/*
> + * Broadwell:
> + * The INST_RETIRED.ALL period always needs to have lowest
> + * 6bits cleared (BDM57). It shall not use a period smaller
> + * than 100 (BDM11). We combine the two to enforce
> + * a min-period of 128.
> + */
> +static unsigned bdw_limit_period(struct perf_event *event, unsigned left)
> +{
> + if ((event->hw.config & 0xffff) == 0x1c0) {
ISTR we have actual proper defines for that.
> + if (left < 128)
> + left = 128;
> + left &= ~0x3fu;
> + }
> + return left;
> +}
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next prev parent reply other threads:[~2014-08-13 8:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-13 1:45 [PATCH 1/3] perf, x86: Remove incorrect model number from Haswell perf Andi Kleen
2014-08-13 1:45 ` [PATCH 2/3] perf, x86: Add Broadwell core support Andi Kleen
2014-08-13 8:00 ` Peter Zijlstra
2014-08-13 1:45 ` [PATCH 3/3] perf, x86: Add INST_RETIRED.PREC_DIST workarounds Andi Kleen
2014-08-13 8:10 ` Peter Zijlstra [this message]
2014-08-13 7:58 ` [PATCH 1/3] perf, x86: Remove incorrect model number from Haswell perf Peter Zijlstra
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