From mboxrd@z Thu Jan 1 00:00:00 1970 From: Britton Date: Thu, 08 Jun 2000 22:25:46 +0000 Subject: Re: how to find the maximum fragment size for SNDCTL_DSP_SETFRAGMENT? Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sound@vger.kernel.org On Fri, 9 Jun 2000, Hannu Savolainen wrote: > On Thu, 8 Jun 2000, Britton wrote: > > > > > The guide of 4front's web page says total_buffer_size/2. I know the > > kernel buffer size used to be defined at kernel compile time. How does > > one go about determining it now? DSP_GETBLKSZ? > Wy would you need this information? I'm letting my users specify the fragment size, and I try to check things like whether what they specify is out of range before actually making the syscall. > If you like to get as large fragments as possible just set the fragment > size to very big. The driver will then select the largest one it could > support. Ok, I didn't know it would do that. I guess there is no real reason the user needs to know if their large fragment size was not actually set (they already get a warning if the fragment size they request is big enough that it will likely cause latency). That behavior might be something to add to the 4front page. > However changing the fragment size bigger than the default doesn't give > any benefit. You can always write/read multiple fragments at time to get > the same effect. > > > Does DSP_GETBLKSZ still > > fix the block size so that the device must be closed and opened again in > > order to set the fragment size? > This is the current and future behaviour. Thanks, Britton