From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [PATCH v3] sched/fair: Add advisory flag for borrowing a timeslice (was: Pre-emption control for userspace) Date: Tue, 25 Nov 2014 08:38:02 -0500 Message-ID: <5474863A.6010307@redhat.com> References: <1416862595-24513-1-git-send-email-khalid.aziz@oracle.com> <5473E388.6000605@redhat.com> <1416897050.20575.18.camel@linux-t7sj.site> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1416897050.20575.18.camel@linux-t7sj.site> Sender: linux-doc-owner@vger.kernel.org To: Davidlohr Bueso Cc: Khalid Aziz , tglx@linutronix.de, corbet@lwn.net, mingo@redhat.com, hpa@zytor.com, peterz@infradead.org, akpm@linux-foundation.org, rientjes@google.com, ak@linux.intel.com, mgorman@suse.de, liwanp@linux.vnet.ibm.com, raistlin@linux.it, kirill.shutemov@linux.intel.com, atomlin@redhat.com, avagin@openvz.org, gorcunov@openvz.org, serge.hallyn@canonical.com, athorlton@sgi.com, oleg@redhat.com, vdavydov@parallels.com, daeseok.youn@gmail.com, keescook@chromium.org, yangds.fnst@cn.fujitsu.com, sbauer@eng.utah.edu, vishnu.ps@samsung.com, axboe@fb.com, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-api@vger.kernel.org List-Id: linux-api@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/25/2014 01:30 AM, Davidlohr Bueso wrote: > On Mon, 2014-11-24 at 21:03 -0500, Rik van Riel wrote: >> I can see this "solution" help mostly with userspace spinlocks, >> which are relics of a past era that need to die. There is no way >> userspace spinlocks will not fail miserably on virtual machines, >> and it is time to get rid of them. > > No, not really. Spinlocks are still very useful on bare metal. > Virtualization is not the only thing out there. How many people are going to build two different binaries, one for bare metal, and one for virtualized environments? I suspect the vast majority of applications will only be built once, and it would be nice if it wasn't using a locking scheme that broke horribly on a significant part of the deployments... - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUdIY6AAoJEM553pKExN6DaisH+wWzTc+onHTsPUXs6EU/s+sa lp3KFWmRQACPjiWSyIfg7aWFxakiS8BQ4ypbXdC/55lHuX/KMm/1k3zZF/lHiyYA vIwfPUX7TnZxgYGVGk++nrCTffQImAc5RXlCBU6Hp6dHxV5Pead6S9afO8dfOeVu 80cpsqCyUqX+jhMDKq6NkIE0mCMb/U4L0cqo7m67h7PTlWmj8V64PKJjvkDu48O1 tPd+6jj4xDoEl8dde00EMaYETA6Utngt8+LslV1hMB1nxn82aNIGJnEqQco4WGXH gE8Pkn+iToBe1hPF63MVZFJHRzXPUOAoaBCTgu7+l9LLDkfBgv2A/ckh5NLUrd8= =41Jl -----END PGP SIGNATURE-----