From: Kaixu Xia <xiakaixu@huawei.com>
To: <ast@plumgrid.com>, <davem@davemloft.net>, <acme@kernel.org>,
<mingo@redhat.com>, <a.p.zijlstra@chello.nl>,
<masami.hiramatsu.pt@hitachi.com>, <jolsa@kernel.org>,
<daniel@iogearbox.net>
Cc: <xiakaixu@huawei.com>, <wangnan0@huawei.com>,
<linux-kernel@vger.kernel.org>, <pi3orama@163.com>,
<hekuang@huawei.com>, <netdev@vger.kernel.org>
Subject: [PATCH V5 0/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling
Date: Tue, 20 Oct 2015 07:22:14 +0000 [thread overview]
Message-ID: <1445325735-121694-1-git-send-email-xiakaixu@huawei.com> (raw)
Previous patch V4 url:
https://lkml.org/lkml/2015/10/19/247
This patchset introduces the new perf_event_attr attribute
'soft_disable'. The already existed 'disabled' flag doesn't
meet the requirements. The cpu_function_call is too much
to do from bpf program and we control the perf_event stored in
maps like soft_disable, so if the 'disabled' flag is set to
true, we can't enable/disable the perf event by bpf programs.
changes in V5:
- move the bpf helper parameter 'flags' defination to bpf_trace.c
and document the flags bits in uapi header.
changes in V4:
- make the naming more proper;
- fix the initial value set of attr->soft_disable bug;
- add unlikely() to the check of event->soft_enable;
- squash the 2ed patch into 1st patch;
changes in V3:
- make the flag name and condition check consistent;
- check the bpf helper flag only bit 0 and check all other bits are
reserved;
- use atomic_dec_if_positive() and atomic_inc_unless_negative();
- make bpf_perf_event_dump_control_proto be static;
- remove the ioctl PERF_EVENT_IOC_SET_ENABLER and 'enabler' event;
- implement the function that controlling all the perf events
stored in PERF_EVENT_ARRAY maps by setting the parameter 'index'
to maps max_entries;
changes in V2:
- rebase the whole patch set to net-next tree(4b418bf);
- remove the added flag perf_sample_disable in bpf_map;
- move the added fields in structure perf_event to proper place
to avoid cacheline miss;
- use counter based flag instead of 0/1 switcher in considering
of reentering events;
- use a single helper bpf_perf_event_sample_control() to enable/
disable events;
- implement a light-weight solution to control the trace data
output on current cpu;
- create a new ioctl PERF_EVENT_IOC_SET_ENABLER to enable/disable
a set of events;
Before this patch,
$ ./perf record -e cycles -a sleep 1
$ ./perf report --stdio
# To display the perf.data header info, please use --header/--header-only option
#
#
# Total Lost Samples: 0
#
# Samples: 527 of event 'cycles'
# Event count (approx.): 87824857
...
After this patch,
$ ./perf record -e pmux=cycles --event perf-bpf.o/my_cycles_map=pmux/ -a sleep 1
$ ./perf report --stdio
# To display the perf.data header info, please use --header/--header-only option
#
#
# Total Lost Samples: 0
#
# Samples: 22 of event 'cycles'
# Event count (approx.): 4213922
...
The bpf program example:
struct bpf_map_def SEC("maps") my_cycles_map = {
.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
.key_size = sizeof(int),
.value_size = sizeof(u32),
.max_entries = 32,
};
SEC("enter=sys_write")
int bpf_prog_1(struct pt_regs *ctx)
{
bpf_perf_event_control(&my_cycles_map, 0, 3);
return 0;
}
SEC("exit=sys_write%return")
int bpf_prog_2(struct pt_regs *ctx)
{
bpf_perf_event_control(&my_cycles_map, 0, 2);
return 0;
}
Consider control sampling in function level, we have to set
a high sample frequency to dump trace data when enable/disable
the perf event on current cpu.
Kaixu Xia (1):
bpf: control events stored in PERF_EVENT_ARRAY maps trace data output
when perf sampling
include/linux/perf_event.h | 1 +
include/uapi/linux/bpf.h | 11 ++++++++
include/uapi/linux/perf_event.h | 3 +-
kernel/bpf/verifier.c | 3 +-
kernel/events/core.c | 13 +++++++++
kernel/trace/bpf_trace.c | 62 +++++++++++++++++++++++++++++++++++++++++
6 files changed, 91 insertions(+), 2 deletions(-)
--
1.8.3.4
next reply other threads:[~2015-10-20 7:27 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-20 7:22 Kaixu Xia [this message]
2015-10-20 7:22 ` [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling Kaixu Xia
2015-10-20 22:53 ` Alexei Starovoitov
2015-10-21 9:12 ` Peter Zijlstra
2015-10-21 10:31 ` xiakaixu
2015-10-21 11:33 ` Peter Zijlstra
2015-10-21 11:49 ` Wangnan (F)
2015-10-21 12:17 ` Peter Zijlstra
2015-10-21 13:42 ` Wangnan (F)
2015-10-21 13:49 ` Peter Zijlstra
2015-10-21 14:01 ` pi3orama
2015-10-21 14:09 ` Peter Zijlstra
2015-10-21 15:06 ` pi3orama
2015-10-21 16:57 ` Peter Zijlstra
2015-10-21 21:19 ` Alexei Starovoitov
2015-10-22 9:06 ` Peter Zijlstra
2015-10-22 10:28 ` Wangnan (F)
2015-10-23 12:52 ` Peter Zijlstra
2015-10-23 15:12 ` Peter Zijlstra
2015-10-27 6:43 ` xiakaixu
2015-10-22 2:46 ` Wangnan (F)
2015-10-22 7:39 ` Ingo Molnar
2015-10-22 7:51 ` Wangnan (F)
2015-10-22 9:24 ` Peter Zijlstra
2015-10-22 1:56 ` Wangnan (F)
2015-10-22 3:09 ` Alexei Starovoitov
2015-10-22 3:12 ` Wangnan (F)
2015-10-22 3:26 ` Alexei Starovoitov
2015-10-22 9:49 ` Peter Zijlstra
2015-10-21 11:34 ` Wangnan (F)
2015-10-21 11:56 ` Peter Zijlstra
2015-10-21 12:03 ` Wangnan (F)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1445325735-121694-1-git-send-email-xiakaixu@huawei.com \
--to=xiakaixu@huawei.com \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@kernel.org \
--cc=ast@plumgrid.com \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=hekuang@huawei.com \
--cc=jolsa@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=masami.hiramatsu.pt@hitachi.com \
--cc=mingo@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=pi3orama@163.com \
--cc=wangnan0@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).