Måns Rullgård <m...@mansr.com> wrote: > Eric Wong <normalper...@yhbt.net> writes: > > > Eric Wong <normalper...@yhbt.net> wrote: > >> All relevant audio file formats store data sequentially, so > >> give a hint to the kernel to perform more readahead. In current > >> Linux, the readahead hint doubles readahead pages and can help > >> with playback on slow devices. > > > > Btw, I've been running this for a few years, too; but pretty > > much all on FLAC. > > > > I don't know if there's audio formats we support which aren't > > sequential. Maybe there's some wacky audio format which > > requires random read all over the place... > > I can't think of any format that isn't mostly sequential, certainly not > that's supported in SoX. There might exist some format that separates > channel data such that reading sequentially from multiple starting > points is the best strategy.
Yeah, I was wondering about something along those lines, especially if exceeding 2 channels... > What sort of improvement do you get from this anyway? I'm not opposed > to the addition, just curious. I didn't measure before :x It's more of a "it couldn't hurt" thing and let the kernel (and configured per-device readahead) decide. It's only intended as a hint for the kernel, after all. My 7200 RPM HDD has 256 MB cache on it; I couldn't measure any difference even with 'echo 3 >/proc/sys/vm/drop_caches' (Linux) and reading ~300 MB of stuff before testing in hopes it'd clear the internal HDD cache. Maybe slower mounts (optical storage, 4200 RPM HDDs, or network FSes) will see the benefit. I used to play audio on a laptop using an sshfs mount back in the day (with FUSE readahead, too), but haven't had the need or ability to do that for years, now. _______________________________________________ SoX-devel mailing list SoX-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sox-devel
