From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754872AbcARMCl (ORCPT <rfc822;w@1wt.eu>);
	Mon, 18 Jan 2016 07:02:41 -0500
Received: from bombadil.infradead.org ([198.137.202.9]:47526 "EHLO
	bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754680AbcARMCj (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 18 Jan 2016 07:02:39 -0500
Date: Mon, 18 Jan 2016 13:02:30 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Wang Nan <wangnan0@huawei.com>
Cc: acme@kernel.org, linux-kernel@vger.kernel.org, pi3orama@163.com,
        lizefan@huawei.com, He Kuang <hekuang@huawei.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        "David S. Miller" <davem@davemloft.net>, Jiri Olsa <jolsa@kernel.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCH] perf core: Introduce new ioctl options to pause and
 resume ring buffer
Message-ID: <20160118120230.GP6357@twins.programming.kicks-ass.net>
References: <20160112141430.GH6357@twins.programming.kicks-ass.net>
 <1453117921-122482-1-git-send-email-wangnan0@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1453117921-122482-1-git-send-email-wangnan0@huawei.com>
User-Agent: Mutt/1.5.21 (2012-12-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Jan 18, 2016 at 11:52:01AM +0000, Wang Nan wrote:

> +#define PERF_EVENT_IOC_PAUSE_OUTPUT	_IO ('$', 9)
> +#define PERF_EVENT_IOC_RESUME_OUTPUT	_IO ('$', 10)

Would not a single IOCTL with a 'boolean' parameter make more sense?

> +++ b/kernel/events/ring_buffer.c
> @@ -125,7 +125,7 @@ int perf_output_begin(struct perf_output_handle *handle,
>  	if (unlikely(!rb))
>  		goto out;
>  
> -	if (unlikely(!rb->nr_pages))
> +	if (unlikely(rb->paused))
>  		goto out;

Should we increment rb->lost in this case?