Increase DFLDSIZ on amd64?

Robert Millan rmh at
Wed Apr 18 21:41:31 UTC 2012


Is there any reason for DFLDSIZ being so low (128 MiB) on amd64?
We've recently had a bunch of trouble in Debian when attempting to run
the CMOR testsuite.  Its testcases require about ~700 MiB to pass.  We
also found references recommending higher values for applications like
SAP [2] or MySQL [3].

I understand on i386 there's a shortage of virtual memory, but on
amd64 there's plenty of it.  It seems this is already reflected on the
MAXDSIZ setting (32 GiB), but DFLDSIZ is still the same as on i386.
Wouldn't 32 GiB be a sound value as the default limit too?  Is there
any unreasonable cost or security consideration associated with
allocating so many pages?



Robert Millan
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