Date: Sat, 30 Aug 1997 22:46:00 -0700 From: Amancio Hasty <hasty@rah.star-gate.com> To: Luigi Rizzo <luigi@labinfo.iet.unipi.it> Cc: dec@phoenix.its.rpi.edu, hackers@FreeBSD.ORG, multimedia@FreeBSD.ORG Subject: Re: IRQ problem (was Re: IRQ timing) Message-ID: <199708310546.WAA00887@rah.star-gate.com> In-Reply-To: Your message of "Sun, 31 Aug 1997 06:24:16 %2B0200." <199708310424.GAA03702@labinfo.iet.unipi.it>
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In guspnpxxx or linux sound driver 3.5 adaption for FreeBSD uses 64kb for the dma buffer, the default size for dma requests is a 1/2 second. If the user specifies a block size the dma buffer gets split in N blocks of the specified user block size and the dma buffer remains 64k. Amancio >From The Desk Of Luigi Rizzo : > > > > o buffer size used in in the application > > > > > > i guess you also need the blocksize -- the size of each DMA transfers > > > -- and not only the total amount of buffers. > > > > True but bear in mind that the system has plenty of memory: > ... > > I would hope that the OSS driver has the heuristics to allocate > > sufficient memory for the buffers. > > I think the default is 64K (seen in some include file). What I am not > sure about is if the blocksize for DMA transfer is determined > adaptively if the user does not call some SETFRAGMENT or SUBDIVIDE > ioctl. In my code I wrote some code to use 0.25s of audio for each DMA > transfer unless the user specifies elsewhere (using the above calls or > the new one that I introduced, AIOSSIZE). > > What about guspnpXX ? > > Luigi
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