From: Alexei Starovoitov <ast@plumgrid•com>
To: Peter Zijlstra <peterz@infradead•org>, Kaixu Xia <xiakaixu@huawei•com>
Cc: davem@davemloft•net, acme@kernel•org, mingo@redhat•com,
masami.hiramatsu.pt@hitachi•com, jolsa@kernel•org,
daniel@iogearbox•net, wangnan0@huawei•com,
linux-kernel@vger•kernel.org, pi3orama@163•com,
hekuang@huawei•com, netdev@vger•kernel.org
Subject: Re: [PATCH v6 3/4] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter
Date: Wed, 5 Aug 2015 09:08:32 -0700 [thread overview]
Message-ID: <55C23500.1000207@plumgrid.com> (raw)
In-Reply-To: <20150805135317.GZ18673@twins.programming.kicks-ass.net>
On 8/5/15 6:53 AM, Peter Zijlstra wrote:
> + /*
> + * If the event is currently on this CPU, its either a per-task event,
> + * or local to this CPU. Furthermore it means its ACTIVE (otherwise
> + * oncpu == -1).
> + */
> + if (event->oncpu == smp_processor_id())
> + event->pmu->read(event);
> +
> + val = local64_read(&event->count);
> + local_irq_restore(flags);
> +
nice! cleaner and faster.
so raw_spin_lock(&ctx->lock) is not needed, because
update_*(event) methods are not called, right?
next prev parent reply other threads:[~2015-08-05 16:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-04 8:58 [PATCH v6 0/4] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Kaixu Xia
2015-08-04 8:58 ` [PATCH v6 1/4] bpf: Make the bpf_prog_array_map more generic Kaixu Xia
2015-08-04 8:58 ` [PATCH v6 2/4] bpf: Add new bpf map type to store the pointer to struct perf_event Kaixu Xia
2015-08-04 17:43 ` Alexei Starovoitov
2015-08-05 9:41 ` Peter Zijlstra
2015-08-05 9:39 ` Peter Zijlstra
2015-08-05 9:43 ` Peter Zijlstra
2015-08-04 8:58 ` [PATCH v6 3/4] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter Kaixu Xia
2015-08-04 17:55 ` Alexei Starovoitov
2015-08-05 2:09 ` xiakaixu
2015-08-05 10:04 ` Peter Zijlstra
2015-08-05 10:15 ` Peter Zijlstra
2015-08-05 16:00 ` Alexei Starovoitov
2015-08-05 10:31 ` xiakaixu
2015-08-05 13:53 ` Peter Zijlstra
2015-08-05 13:59 ` Peter Zijlstra
2015-08-05 16:08 ` Alexei Starovoitov [this message]
2015-08-05 16:21 ` Peter Zijlstra
2015-08-06 2:49 ` xiakaixu
2015-08-05 15:59 ` Alexei Starovoitov
2015-08-04 8:58 ` [PATCH v6 4/4] samples/bpf: example of get selected PMU counter value Kaixu Xia
2015-08-05 10:06 ` [PATCH v6 0/4] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Peter Zijlstra
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