From: Peter Zijlstra <peterz@infradead.org>
To: Leo Yan <leo.yan@linaro.org>
Cc: Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Paul Cercueil <paul@crapouillou.net>,
"Ben Dooks (Codethink)" <ben.dooks@codethink.co.uk>,
"Ahmed S. Darwish" <a.darwish@linutronix.de>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/6] arm64: perf: Implement correct cap_user_time
Date: Wed, 15 Jul 2020 10:38:00 +0200
Message-ID: <20200715083800.GC10769@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200715020512.20991-3-leo.yan@linaro.org>
On Wed, Jul 15, 2020 at 10:05:08AM +0800, Leo Yan wrote:
> [leoyan: Use quot/rem to convert cyc to ns to avoid overflow]
> + quot = rd->epoch_cyc >> rd->shift;
> + rem = rd->epoch_cyc & (((u64)1 << rd->shift) - 1);
> + ns = quot * rd->mult + ((rem * rd->mult) >> rd->shift);
> + userpg->time_zero -= ns;
I think we have mul_u64_u32_shr() for that.
next prev parent reply index
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 2:05 [PATCH v2 0/6] arm64: perf: Proper cap_user_time* support Leo Yan
2020-07-15 2:05 ` [PATCH v2 1/6] sched_clock: Expose struct clock_read_data Leo Yan
2020-07-15 5:56 ` Ahmed S. Darwish
2020-07-15 6:54 ` Leo Yan
2020-07-15 7:21 ` Ahmed S. Darwish
2020-07-15 8:12 ` Peter Zijlstra
2020-07-15 8:14 ` peterz
2020-07-15 9:23 ` Ahmed S. Darwish
2020-07-15 9:52 ` Peter Zijlstra
2020-07-15 11:59 ` [PATCH] time/sched_clock: Use raw_read_seqcount_latch() Ahmed S. Darwish
2020-07-15 15:29 ` Leo Yan
2020-07-15 15:58 ` Peter Zijlstra
2020-07-16 5:22 ` Leo Yan
2020-09-10 15:08 ` [tip: locking/core] time/sched_clock: Use raw_read_seqcount_latch() during suspend tip-bot2 for Ahmed S. Darwish
2020-07-15 2:05 ` [PATCH v2 2/6] arm64: perf: Implement correct cap_user_time Leo Yan
2020-07-15 8:38 ` Peter Zijlstra [this message]
2020-07-15 15:39 ` Leo Yan
2020-07-15 2:05 ` [PATCH v2 3/6] arm64: perf: Only advertise cap_user_time for arch_timer Leo Yan
2020-07-15 2:05 ` [PATCH v2 4/6] perf: Add perf_event_mmap_page::cap_user_time_short ABI Leo Yan
2020-07-15 2:05 ` [PATCH v2 5/6] arm64: perf: Add cap_user_time_short Leo Yan
2020-07-15 2:05 ` [PATCH v2 6/6] tools headers UAPI: Update tools's copy of linux/perf_event.h Leo Yan
2020-07-15 5:17 ` [PATCH v2 0/6] arm64: perf: Proper cap_user_time* support Ahmed S. Darwish
2020-07-15 6:29 ` Leo Yan
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