Re: Degenerate file access patterns

[David Kastrup]

Trevor <address@hidden> writes:

> I'm trying to run LilyPond in Google Cloud Functions
> <https://cloud.google.com/functions/>, and execution is ridiculously slow
> (like 40 seconds compilation vs. 2 seconds on my laptop). A Google Cloud
> engineer tested it and reported the following:
>
> "The culprit is that the lilypond binary has a bit sub-optimal file
> access pattern (opening the same file thousands of times and reading
> it byte by byte, causing a syscall flood - nearly 500K lseek and read
> operations). On a local machine, because of this issue, it will spend
> about 1s in I/O syscalls, which is half of the total execution
> time. This currently does not play nice with our systems, getting it
> from 1s to over half a minute."

I suspect this is rather related to memory mapping files (either for
storage management or for input).

So it would be good to know just what files we are talking about here.

-- 
David Kastrup