Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261790AbVAHFiR (ORCPT ); Sat, 8 Jan 2005 00:38:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261793AbVAHFiR (ORCPT ); Sat, 8 Jan 2005 00:38:17 -0500 Received: from mail21.syd.optusnet.com.au ([211.29.133.158]:61336 "EHLO mail21.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S261790AbVAHFiC (ORCPT ); Sat, 8 Jan 2005 00:38:02 -0500 Message-ID: <41DF7179.20401@kolivas.org> Date: Sat, 08 Jan 2005 16:36:57 +1100 From: Con Kolivas User-Agent: Mozilla Thunderbird 1.0 (X11/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Takashi Iwai Cc: Arjan van de Ven , Paul Davis , Christoph Hellwig , Lee Revell , Ingo Molnar , Chris Wright , Alan Cox , "Jack O'Quin" , Linux Kernel Mailing List , Andrew Morton Subject: Re: [PATCH] [request for inclusion] Realtime LSM References: <20050107153328.GD28466@devserv.devel.redhat.com> <200501071541.j07FfeQC018553@localhost.localdomain> <20050107160350.GB29327@devserv.devel.redhat.com> In-Reply-To: X-Enigmail-Version: 0.89.5.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig7EA41A00C142D7F40711CFE2" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2209 Lines: 52 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig7EA41A00C142D7F40711CFE2 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Takashi Iwai wrote: > At Fri, 7 Jan 2005 17:03:51 +0100, > Arjan van de Ven wrote: >>something like a soft realtime flag that acts as if it's the hard realtime >>one unless the app shows "misbehavior" (eg eats its timeslice for X times in >>a row) might for example be such a solution. And with the anti abuse >>protection it can run with far lighter privilegs. > > > This reminds me about the soft-RT patch posted quite sometime ago. > I feel such a handy psuedo-RT scheduler class would be useful for > other systems than JACK, too... You've already proven that soft RT does not suit your requirements. The current scheduler running a task at nice -20 has extremely long periods of cpu availability at the expense of lower priority tasks and is close to the behaviour you would get with a soft RT patch. Your concern is exactly the scenario where nice -20 fails, and would be the same scenario where a soft RT policy would fail. Doing this with a scheduling policy, you want cpu time long after there is any hope for fairness or safety of hanging. From experimentation with such soft RT policies, we find average latencies can be reduced but the maximum ones, which are the ones that concern professional audio, remain the same. Cheers, Con --------------enig7EA41A00C142D7F40711CFE2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFB33F7ZUg7+tp6mRURAtuhAJ92OZB00mcbbiPGsZX/t2qaEm8aIwCglGAp qoiw0x+0vUdbdIrEWu1+AEA= =XDFH -----END PGP SIGNATURE----- --------------enig7EA41A00C142D7F40711CFE2-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/