From: Kris Van Hees <kris.van.hees@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Kris Van Hees <kris.van.hees@oracle.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
dtrace-devel@oss.oracle.com, linux-kernel@vger.kernel.org,
rostedt@goodmis.org, mhiramat@kernel.org, acme@kernel.org,
ast@kernel.org, daniel@iogearbox.net, Chris Mason <clm@fb.com>
Subject: Re: [PATCH 1/1] tools/dtrace: initial implementation of DTrace
Date: Mon, 8 Jul 2019 12:38:11 -0400 [thread overview]
Message-ID: <20190708163811.GB20847@oracle.com> (raw)
In-Reply-To: <20190704130509.GO3402@hirez.programming.kicks-ass.net>
On Thu, Jul 04, 2019 at 03:05:09PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 03, 2019 at 08:14:30PM -0700, Kris Van Hees wrote:
> > +int dt_bpf_attach(int event_id, int bpf_fd)
> > +{
> > + int event_fd;
> > + int rc;
> > + struct perf_event_attr attr = {};
> > +
> > + attr.type = PERF_TYPE_TRACEPOINT;
> > + attr.sample_type = PERF_SAMPLE_RAW;
> > + attr.sample_period = 1;
> > + attr.wakeup_events = 1;
> > + attr.config = event_id;
> > +
> > + /* Register the event (based on its id), and obtain a fd. */
> > + event_fd = perf_event_open(&attr, -1, 0, -1, 0);
> > + if (event_fd < 0) {
> > + perror("sys_perf_event_open");
> > + return -1;
> > + }
> > +
> > + /* Enable the probe. */
> > + rc = ioctl(event_fd, PERF_EVENT_IOC_ENABLE, 0);
>
> AFAICT you didn't use attr.disabled = 1, so this IOC_ENABLE is
> completely superfluous.
Oh yes, good point (and the same applies to the dt_buffer.c code where I set
up the events that own each buffer - no point in doing an explicit enable there
eiteher).
Thanks for catching this!
> > + if (rc < 0) {
> > + perror("PERF_EVENT_IOC_ENABLE");
> > + return -1;
> > + }
> > +
> > + /* Associate the BPF program with the event. */
> > + rc = ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, bpf_fd);
> > + if (rc < 0) {
> > + perror("PERF_EVENT_IOC_SET_BPF");
> > + return -1;
> > + }
> > +
> > + return 0;
> > +}
next prev parent reply other threads:[~2019-07-08 16:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-04 3:13 [PATCH 0/1] tools/dtrace: initial implementation of DTrace Kris Van Hees
2019-07-04 3:14 ` [PATCH 1/1] " Kris Van Hees
2019-07-04 13:03 ` Peter Zijlstra
2019-07-08 16:48 ` Kris Van Hees
2019-07-04 13:05 ` Peter Zijlstra
2019-07-08 16:38 ` Kris Van Hees [this message]
2019-07-04 17:13 ` Brendan Gregg
2019-07-08 17:15 ` Arnaldo Carvalho de Melo
2019-07-08 22:38 ` Kris Van Hees
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