From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCHv8 02/34] lib/vdso: make do_hres and do_coarse as __always_inline
Date: Fri, 10 Jan 2020 12:42:45 +0100
Message-ID: <878smfa66i.fsf@nanos.tec.linutronix.de>
References: <20191112012724.250792-1-dima@arista.com> <20191112012724.250792-3-dima@arista.com> <ed2e65ae-75b0-ed79-0a95-90be6b82e6be@arm.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8BIT
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <ed2e65ae-75b0-ed79-0a95-90be6b82e6be@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
To: Vincenzo Frascino <vincenzo.frascino@arm.com>, Dmitry Safonov <dima@arista.com>, linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>, Andrei Vagin <avagin@gmail.com>, Adrian Reber <adrian@lisas.de>, Andrei Vagin <avagin@openvz.org>, Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>, Christian Brauner <christian.brauner@ubuntu.com>, Cyrill Gorcunov <gorcunov@openvz.org>, "Eric W. Biederman" <ebiederm@xmission.com>, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>, Jann Horn <jannh@google.com>, Jeff Dike <jdike@addtoit.com>, Oleg Nesterov <oleg@redhat.com>, Pavel Emelyanov <xemul@virtuozzo.com>, Shuah Khan <shuah@kernel.org>, containers@lists.linux-foundation.org, criu@openvz.org, linux-api@vger.kernel.org, x86@kernel.org
List-Id: linux-api@vger.kernel.org

Vincenzo Frascino <vincenzo.frascino@arm.com> writes:
> On 11/12/19 1:26 AM, Dmitry Safonov wrote:
>> +» » vd·=·&vd[CS_HRES_COARSE];
>> +out_hres:
>> +» » return·do_hres(vd,·clock,·ts);
>> » }·else·if·(msk·&·VDSO_COARSE)·{
>> » » do_coarse(&vd[CS_HRES_COARSE],·clock,·ts);
>> » » return·0;
>> » }·else·if·(msk·&·VDSO_RAW)·{
>> -» » return·do_hres(&vd[CS_RAW],·clock,·ts);
>> +» » vd·=·&vd[CS_RAW];
>> +» » /*·goto·allows·to·avoid·extra·inlining·of·do_hres.·*/
>> +» » goto·out_hres;
>
> What is the performance impact of "goto out_hres"?

On x86 it's invisible at least in my limited testing.

Thanks,

        tglx