From: Peter Zijlstra <peterz@infradead.org>
To: "Suzuki K. Poulose" <Suzuki.Poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
punit.agrawal@arm.com, arm@kernel.org
Subject: Re: [PATCH v4 05/12] arm-cci: PMU: Add support for transactions
Date: Fri, 18 Dec 2015 12:47:51 +0100 [thread overview]
Message-ID: <20151218114751.GP6344@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <5673E6C9.7040304@arm.com>
On Fri, Dec 18, 2015 at 10:58:17AM +0000, Suzuki K. Poulose wrote:
> We have a global Enable/Disable for CCI PMU and thats what we use
> currently. To be able to reprogram the counters with the event period
> (we program the counter with a specific count in pmu::start() and at
> overflow irq handler, not to be confused with the sampling period, which
> is not supported), we need to be sure that the counter value has been updated.
>
> May be we could check the event->hw->state to see if we need to reprogram it.
Right, have a look at arch/x86/kernel/cpu/perf_event.c:x86_pmu_enable()
If there's new events, it does two loops over the events.
The first loop does stop(PERF_EF_UPDATE) any counter that got moved.
The second loop does start(PERF_EF_RELOAD) on moved and new events.
The PERF_HES_ARCH bit is used to preserve the stopped state of counters
that were programmed but temporarily stopped.
next prev parent reply other threads:[~2015-12-18 11:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-17 17:49 [PATCHv4 00/12] arm-cci: PMU updates Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 01/12] arm-cci: Define CCI counter period Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 02/12] arm-cci: Refactor pmu_write_counter Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 03/12] arm-cci: Group writes to counter Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 04/12] arm-cci: Fix the flags for pmu_start called from pmu_add Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 05/12] arm-cci: PMU: Add support for transactions Suzuki K. Poulose
2015-12-17 18:42 ` Peter Zijlstra
2015-12-18 10:28 ` Suzuki K. Poulose
2015-12-18 10:42 ` Peter Zijlstra
2015-12-18 10:58 ` Suzuki K. Poulose
2015-12-18 11:47 ` Peter Zijlstra [this message]
2015-12-21 10:55 ` Suzuki K. Poulose
2016-01-05 13:37 ` Peter Zijlstra
2016-01-05 13:43 ` Suzuki K. Poulose
2016-01-05 14:53 ` Peter Zijlstra
2015-12-17 17:49 ` [PATCH v4 06/12] arm-cci: Refactor CCI PMU enable/disable methods Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 07/12] arm-cci: Get the status of a counter Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 08/12] arm-cci: Add routines to save/restore all counters Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 09/12] arm-cci: Provide hook for writing to PMU counters Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 10/12] arm-cci: CCI-500: Work around PMU counter writes Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 11/12] arm-cci500: Rearrange PMU driver for code sharing with CCI-550 PMU Suzuki K. Poulose
2015-12-17 17:49 ` [PATCH v4 12/12] arm-cci: CoreLink CCI-550 PMU driver Suzuki K. Poulose
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