linux-kernel - Re: [PATCH v2 5/5] samples/bpf: example of get selected PMU counter value

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Date:	Wed, 22 Jul 2015 18:16:08 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Kaixu Xia <xiakaixu@...wei.com>, davem@...emloft.net,
	acme@...nel.org, mingo@...hat.com, a.p.zijlstra@...llo.nl,
	masami.hiramatsu.pt@...achi.com, jolsa@...nel.org
Cc:	wangnan0@...wei.com, linux-kernel@...r.kernel.org,
	pi3orama@....com, hekuang@...wei.com
Subject: Re: [PATCH v2 5/5] samples/bpf: example of get selected PMU counter
 value

On 7/22/15 1:09 AM, Kaixu Xia wrote:
> +SEC("kprobe/sys_write")
> +int bpf_prog1(struct pt_regs *ctx)
> +{
> +	u64 count;
> +	u32 key = bpf_get_smp_processor_id();
> +	char fmt[] = "bpf count: CPU-%d  %llu\n";
> +
> +	count = bpf_perf_event_read(&my_map, &key);
> +	bpf_trace_printk(fmt, sizeof(fmt), key, count);
> +
> +	return 0;
> +}

overall the whole thing looks much better, but since you can print
anything, print some sensible string here instead of 'bpf count'.

Thanks!

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