Re: [PATCH 0/2] Improve documentation of FADV_DONTNEED behaviour

From: Michael Kerrisk (man-pages)
Date: Tue Dec 30 2014 - 15:51:36 EST

On Wed, Dec 3, 2014 at 1:42 AM, Mel Gorman <mgorman@xxxxxxx> wrote:
> Partial page discard requests are ignored and the documentation on why this
> is correct behaviour sucks. A readahead patch looked like a "regression" to
> a random IO storage benchmark because posix_fadvise() was used incorrectly
> to force IO requests to go to disk. In reality, the benchmark sucked but
> it was non-obvious why. Patch 1 updates the kernel comment in case someone
> "fixes" either readahead or fadvise for inappropriate reasons. Patch 2
> updates the relevant man page on the rough off chance that application
> developers do not read kernel source comments.

It feels like that last sentence should have made LWN quote of the week :-/.

Michael Kerrisk
Linux man-pages maintainer;
Linux/UNIX System Programming Training:
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at