From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Revell Subject: Re: Re: [Jackit-devel] irq handler top half timestamps Date: Mon, 20 Dec 2004 20:49:01 -0500 Message-ID: <1103593741.8297.18.camel@krustophenia.net> References: <200412102051.iBAKphFL012668@localhost.localdomain> <1102712509.29919.46.camel@krustophenia.net> <20041211015610.1798af34@mango.fruits.de> <20041211032214.5121a003@mango.fruits.de> <20041216003255.6e65360b@mango.fruits.de> <20041216091812.GE11047@elte.hu> <20041216173353.4348dd15@mango.fruits.de> <1103222119.23735.2.camel@krustophenia.net> <20041220004511.579be209@mango.fruits.de> <1103499499.32415.35.camel@krustophenia.net> <20041220160855.699a1014@mango.fruits.de> <20041221023043.513bc7fb@mango.fruits.de> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20041221023043.513bc7fb@mango.fruits.de> Sender: alsa-devel-admin@lists.sourceforge.net Errors-To: alsa-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Florian Schmidt Cc: tapas , Ingo Molnar , Paul Davis , Jaroslav Kysela , jackit-devel@lists.sourceforge.net, alsa-devel List-Id: alsa-devel@alsa-project.org On Tue, 2004-12-21 at 02:30 +0100, Florian Schmidt wrote: > On Mon, 20 Dec 2004 16:08:55 +0100 > Florian Schmidt wrote: > > > I see. And all these calls have constant execution time? > > Oops, i should read more carefully. sorry. > Well, it would be interesting to measure the variance due to the trigger callback in the driver. Usually this just does a single inl() to read the pointer from the hardware, then a bit of arithmetic (bytes_to_frames or whatever). I think the variance will be a function of PCI bus contention. It would be great to have some numbers, though. Also for testing purposes it would be trivial to add another timestamp mode to ALSA, where the timestamp is taken as soon as possible in the interrupt handler, instead of doing it after getting the pointer from the hw. Lee ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/