bakker_be wrote: > I second this report, I'd just like to know whether MMAP on the > Squeezelite-page is dealing with this:http://en.wikipedia.org/wiki/Mmap? > Its use isn't really clear to me, so I guess that for Joe Q. Public it > will be even less so. A little additional info would come in handy, > especially for people who aren't Linux savvy.
I'm going to do a really crap job of explaining this. (Not on purpose, I'm just not very good at explaining things.) >From a music playing user perspective, if that MMAP param is not populated with either zero or one, squeezelite tries to open the device using MMAP, and if that is not possible, (ie. the device doesn't support it), it falls back to opening read/write. The only time you probably want to set that MMAP param, is when you know for sure a device driver doesn't support MMAP mode, so it doesn't try to use it..... Bottom line.... Or from a music playing user perspective interested in the techie stuff, MMAP access is more efficient. And efficiency is all important on a low powered ARM device, where CPU and RAM are more precious than on an over-specified desktop machine. With MMAP, data from 'a' goes directly to 'c', where 'a' is the music data in squeezelite and 'c' is the audio device, 'a' -> 'c'. (A simplification, but it makes this easy to understand.) Without MMAP, there is an intermediate buffer, 'b'. 'a' -> 'b' -> 'c'. Copying data into and out of that 'b' buffer chews up CPU cycles. Using MMAP, the data is transferred 'a' -> 'b' using pointers, rather than copying it via an intermediate buffer. Triode can probably to a way better job of explaining this..... ------------------------------------------------------------------------ JackOfAll's Profile: http://forums.slimdevices.com/member.php?userid=3069 View this thread: http://forums.slimdevices.com/showthread.php?t=99395 _______________________________________________ unix mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/unix
