On 13.11.24 05:19, Matthew Wilcox wrote:
On Tue, Nov 12, 2024 at 04:19:07PM +0100, David Hildenbrand wrote:
Someone configured: "Don't readahead more than 128KiB"
Did they, though? I have nothing but contempt for the thousands of
parameters that we expect sysadmins to configure. It's ridiculous and
it needs to stop. So, we listen to the program that has told us "We
want 2MB pages" and not to the sysadmin who hasn't changed the value of
readahead from one that was originally intended for floppy discs.
If something can be achieved using MADV_HUGEPAGE but not using
auto-tuning (ordinary readahead / no MADV_HUGEPAGE) it's a warning sign
at least to me ...
FWIW, I agree that the parameters we have are confusing. But selectively
ignoring them ... I don't know.
If the parameter is effectively useless on some devices (except floppy
discs?) maybe it should be set to "0=auto" (and modification attempts
failing/being ignored) or simply ignore for all of readahead.
Anyhow, your call. I'll see if I can make sense of the code and come up
with a comment that explains the situation.
--
Cheers,
David / dhildenb
