From mboxrd@z Thu Jan 1 00:00:00 1970 From: Clemens Ladisch Subject: Re: snd_dummy on Centos - Redhat Date: Thu, 03 Sep 2009 15:05:59 +0200 Message-ID: <4A9FBF37.6030106@ladisch.de> References: <7c5010d60909020912k1b9b64bdsab2363c4762e8c5c@mail.gmail.com> <4A9E9CB7.8040809@ladisch.de> <7c5010d60909020933n47381069uacadd656aa98e8e8@mail.gmail.com> <4A9FAD82.3050207@ladisch.de> <7c5010d60909030529w7f226cc1s18c80f1eb0deab3a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from out1.smtp.messagingengine.com (out1.smtp.messagingengine.com [66.111.4.25]) by alsa0.perex.cz (Postfix) with ESMTP id 1768B2452E for ; Thu, 3 Sep 2009 15:06:04 +0200 (CEST) In-Reply-To: <7c5010d60909030529w7f226cc1s18c80f1eb0deab3a@mail.gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Giovanni Maruzzelli Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org Giovanni Maruzzelli wrote: > Yes, CONFIG_PREEMPT* are probably different between the various > kernels, and also the compiled kernel is tickless. > > But, this is a problem only with snd-dummy. The interrupts of other drivers are based on the PCM stream clock, but the snd-dummy driver has to emulate interrupts using the system timer, so it is the only one affected by timer-related changes. > What I would like, in the interest of users, is snd-dummy to be > modified in a way that makes it working on the regular CentOS-RHEL > kernels, The driver relies on the kernel's system timer. It might be possible to rewrite it to use high-resolution timers, if the CentOS kernels supports it. It would be easier to try to change the constraints of the sound card that snd-dummy tries to emulate; set USE_PERIODS_MIN to four or so, and increase period_bytes_min to some value that is at least as large as the numer of bytes per timer tick (with 2 channels and 16 bits at 48 kHz, there are 192000 bytes per second). HTH Clemens