From: Peter Zijlstra <peterz@infradead.org>
To: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Vineet.Gupta1@synopsys.com, arc-linux-dev@synopsys.com,
arnd@arndb.de, Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [PATCH v2 3/8] ARCv2: perf: implement "event_set_period" for future use with interrupts
Date: Tue, 18 Aug 2015 19:52:03 +0200 [thread overview]
Message-ID: <20150818175203.GM20948@worktop> (raw)
In-Reply-To: <1438787614-14074-4-git-send-email-abrodkin@synopsys.com>
On Wed, Aug 05, 2015 at 06:13:29PM +0300, Alexey Brodkin wrote:
> Even though this hardware implementation allows for more flexibility,
> in Linux kernel we decided to mimic behavior of other architectures this
> way:
>
> [1] Set limit value as half of counter's max value (to allow counter to
> run after reaching it limit, see below for more explanation):
> ---------->8-----------
> arc_pmu->max_period = (1ULL << counter_size) / 2 - 1ULL;
> ---------->8-----------
> @@ -317,10 +365,11 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
> return -ENOMEM;
>
> arc_pmu->n_counters = pct_bcr.c;
> - arc_pmu->counter_size = 32 + (pct_bcr.s << 4);
> + counter_size = 32 + (pct_bcr.s << 4);
> + arc_pmu->max_period = (1ULL << counter_size) - 1ULL;
>
I don't see that /2 there..
next prev parent reply other threads:[~2015-08-18 17:52 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-05 15:13 [PATCH v2 0/8] ARCv2 port to Linux - (C) perf Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 1/8] ARC: perf: support RAW events Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 2/8] ARC: perf: cap the number of counters to hardware max of 32 Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 3/8] ARCv2: perf: implement "event_set_period" for future use with interrupts Alexey Brodkin
2015-08-18 17:52 ` Peter Zijlstra [this message]
2015-08-18 18:03 ` Alexey Brodkin
2015-08-20 10:46 ` Alexey Brodkin
2015-08-18 17:55 ` Peter Zijlstra
2015-08-20 11:25 ` Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 4/8] ARCv2: perf: Support sampling events using overflow interrupts Alexey Brodkin
2015-08-18 22:12 ` Peter Zijlstra
2015-08-20 11:30 ` Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 5/8] ARCv2: perf: set usable max period as a half of real max period Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 6/8] ARCv2: perf: implement exclusion of event counting in user or kernel mode Alexey Brodkin
2015-08-18 23:37 ` Peter Zijlstra
2015-08-20 11:33 ` Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 7/8] ARCv2: perf: SMP support Alexey Brodkin
2015-08-05 15:13 ` [PATCH v2 8/8] ARCv2: perf: Finally introduce HS perf unit Alexey Brodkin
2015-08-10 8:29 ` [PATCH v2 0/8] ARCv2 port to Linux - (C) perf Alexey Brodkin
2015-08-14 7:41 ` [arc-linux-dev] " Vineet Gupta
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