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From: xiakaixu <xiakaixu@huawei.com>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: <davem@davemloft.net>, <acme@kernel.org>, <mingo@redhat.com>,
	<a.p.zijlstra@chello.nl>, <masami.hiramatsu.pt@hitachi.com>,
	<jolsa@kernel.org>, <wangnan0@huawei.com>,
	<linux-kernel@vger.kernel.org>, <pi3orama@163.com>,
	<hekuang@huawei.com>
Subject: Re: [PATCH v3 3/3] samples/bpf: example of get selected PMU counter value
Date: Fri, 24 Jul 2015 09:54:01 +0800	[thread overview]
Message-ID: <55B19AB9.3090100@huawei.com> (raw)
In-Reply-To: <55B171EB.30203@plumgrid.com>

于 2015/7/24 6:59, Alexei Starovoitov 写道:
> On 7/23/15 2:42 AM, Kaixu Xia wrote:
>> This is a simple example and shows how to use the new ability
>> to get the selected Hardware PMU counter value.
>>
>> Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
> ...
>> +struct bpf_map_def SEC("maps") my_map = {
>> +    .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
>> +    .key_size = sizeof(int),
>> +    .value_size = sizeof(unsigned long),
>> +    .max_entries = 32,
>> +};
> 
> wait. how did it work here? value_size should be u32.

I tested the whole thing on ARM board. You are ringt, it
should be u32.
When create the array map, we choose the array->elem_size as
round_up(attr->value_size, 8), why 8?

Thanks!
> 
> 
> 



  reply	other threads:[~2015-07-24  1:54 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-23  9:42 [PATCH v3 0/3] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Kaixu Xia
2015-07-23  9:42 ` [PATCH v3 1/3] bpf: Add new bpf map type to store the pointer to struct perf_event Kaixu Xia
2015-07-23 22:54   ` Alexei Starovoitov
2015-07-24  2:22     ` xiakaixu
2015-07-24  2:26       ` Alexei Starovoitov
2015-08-03  9:38   ` Peter Zijlstra
2015-07-23  9:42 ` [PATCH v3 2/3] bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter Kaixu Xia
2015-07-23 22:56   ` Alexei Starovoitov
2015-07-24  1:57     ` xiakaixu
2015-08-03  9:34   ` Peter Zijlstra
2015-08-03 10:32     ` xiakaixu
2015-07-23  9:42 ` [PATCH v3 3/3] samples/bpf: example of get selected PMU counter value Kaixu Xia
2015-07-23 22:59   ` Alexei Starovoitov
2015-07-24  1:54     ` xiakaixu [this message]
2015-07-24  2:23       ` Alexei Starovoitov

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