From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: "Wangnan (F)" <wangnan0@huawei.com>
Cc: arnaldo.melo@gmail.com, linux-kernel@vger.kernel.org,
He Kuang <hekuang@huawei.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@kernel.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Namhyung Kim <namhyung@kernel.org>, Zefan Li <lizefan@huawei.com>,
pi3orama@163.com
Subject: Re: [PATCH 09/17] perf tools: Detect avalibility of write_backward
Date: Fri, 20 May 2016 12:39:02 -0300 [thread overview]
Message-ID: <20160520153902.GB8897@kernel.org> (raw)
In-Reply-To: <573F2DE0.8090003@huawei.com>
Em Fri, May 20, 2016 at 11:31:44PM +0800, Wangnan (F) escreveu:
>
>
> On 2016/5/13 21:08, Arnaldo Carvalho de Melo wrote:
> > Em Fri, May 13, 2016 at 07:56:06AM +0000, Wang Nan escreveu:
> > > Detect avalibility of write_backward and save the result into
> > > record_opts. With write_backward the start pointer of a ring
> > > buffer mapped read only can be found reliably.
> > We have perf_missing_features for that, please try to use it.
>
> I'll try it, but write_backward can't fallback, if kernel doesn't
> support it, I think we'd better throw an error earlier. Using
> perf_missing_features we get error during opening the event, so if we want
> to fail earlier we still need API probing.
Conceptually 'perf_missing_features' shouldn't be strictly tied to
fallbacking, its just a way to mark what perf features are missing in
the current kernel, that info may be used for fallbacking, or for any
other purpose.
- Arnaldo
next prev parent reply other threads:[~2016-05-20 15:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-13 7:55 [PATCH 00/17] perf tools: Support overwritable ring buffer Wang Nan
2016-05-13 7:55 ` [PATCH 01/17] perf tools: Extract __perf_evlist__mmap_read() Wang Nan
2016-05-13 13:03 ` Arnaldo Carvalho de Melo
2016-05-13 7:55 ` [PATCH 02/17] perf tools: Add evlist channel helpers Wang Nan
2016-05-13 13:05 ` Arnaldo Carvalho de Melo
2016-05-18 3:27 ` Wangnan (F)
2016-05-18 13:23 ` Arnaldo Carvalho de Melo
2016-05-13 7:56 ` [PATCH 03/17] perf tools: Automatically add new channel according to evlist Wang Nan
2016-05-13 7:56 ` [PATCH 04/17] perf tools: Operate multiple channels Wang Nan
2016-05-13 7:56 ` [PATCH 05/17] perf record: Prevent reading invalid data in record__mmap_read Wang Nan
2016-05-13 7:56 ` [PATCH 06/17] perf tools: Squash overwrite setting into channel Wang Nan
2016-05-13 7:56 ` [PATCH 07/17] perf record: Don't read from and poll overwrite channel Wang Nan
2016-05-13 7:56 ` [PATCH 08/17] perf record: Don't poll on " Wang Nan
2016-05-13 13:12 ` Arnaldo Carvalho de Melo
2016-05-16 3:18 ` Wangnan (F)
2016-05-13 7:56 ` [PATCH 09/17] perf tools: Detect avalibility of write_backward Wang Nan
2016-05-13 13:08 ` Arnaldo Carvalho de Melo
2016-05-20 15:31 ` Wangnan (F)
2016-05-20 15:39 ` Arnaldo Carvalho de Melo [this message]
2016-05-13 7:56 ` [PATCH 10/17] perf tools: Enable overwrite settings Wang Nan
2016-05-16 13:38 ` Arnaldo Carvalho de Melo
2016-05-13 7:56 ` [PATCH 11/17] perf tools: Set write_backward attribut bit for overwrite events Wang Nan
2016-05-13 7:56 ` [PATCH 12/17] perf tools: Record fd into perf_mmap Wang Nan
2016-05-13 7:56 ` [PATCH 13/17] perf tools: Add API to pause a channel Wang Nan
2016-05-13 7:56 ` [PATCH 14/17] perf record: Rename variable to make code clear Wang Nan
2016-05-13 7:56 ` [PATCH 15/17] perf record: Read from backward ring buffer Wang Nan
2016-05-13 7:56 ` [PATCH 16/17] perf record: Toggle overwrite ring buffer for reading Wang Nan
2016-05-13 7:56 ` [PATCH 17/17] perf tools: Don't warn about out of order event if write_backward is used Wang Nan
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