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 S1753093AbdHJStG (ORCPT <rfc822;w@1wt.eu>);
        Thu, 10 Aug 2017 14:49:06 -0400
Received: from mail-io0-f195.google.com ([209.85.223.195]:35783 "EHLO
        mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752767AbdHJStF (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 10 Aug 2017 14:49:05 -0400
From: Vince Weaver <vincent.weaver@maine.edu>
X-Google-Original-From: Vince Weaver <vince@maine.edu>
Date: Thu, 10 Aug 2017 14:48:52 -0400 (EDT)
X-X-Sender: vince@macbook-air
To: linux-kernel@vger.kernel.org
cc: Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Subject: perf: multiple mmap of fd behavior on x86/ARM
Message-ID: <alpine.DEB.2.20.1708101448460.30979@macbook-air>
User-Agent: Alpine 2.20 (DEB 67 2015-01-07)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


So I was working on my perf_event_tests on ARM/ARM64 (the end goal was to 
get ARM64 rdpmc support working, but apparently those patches never made 
it upstream?)

anyway one test was failing due to an x86/arm difference, which is 
possibly only tangentially perf related.

On x86 you can mmap() a perf_event_open() file descriptor multiple times 
and it works.

On ARM/ARM64 you can only mmap() it once, any other attempts fail.

Is this expected behavior?

You can run the
	tests/record_sample/mmap_multiple
test in the current git of my perf_event_tests testsuite for a testcase.

Vince