[LAD] [LAU] cancelling I/O with libsndfile

Dan Muresan danmbox at gmail.com
Tue Jul 5 05:15:23 UTC 2011


> I haven't measured it, but my educated guess is that if you're
> reading 16384 frames at a time from a FLAC file on current hardware,
> then the difference between reading st_blksize sized blocks and

Uh, actually no. If one reads 4096, 2048, or 1024 frames the result is
the same -- 4 bytes less than st_blksize -- EVERY syscall. Try it. In
any case, I didn't optimize anything like that yet. It was a design
discussion. I was saying that's one more reason why it's good to have
the VIO layer, since there is no userspace cache.

> non-st_blksize sized blocks will be absolutley swamped, by disk
> latencies, cache latencies, scheduling latencies and file
> decoding overhead.

You seem to mix up latency and CPU load? A program can have low
latency, yet high(er than necessary) CPU load.

-- Dan



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