On Wed, 04 Feb 2009 22:26:51 -0800 (PST) David Miller <davem@xxxxxxxxxxxxx> wrote: > I also noticed that when S390 got virtual memmap support, it acquired > the HOLES_IN_ZONE setting as well, in this commit: > > commit f4eb07c17df2e6cf9bd58bfcd9cc9e05e9489d07 > Author: Heiko Carstens <heiko.carstens@xxxxxxxxxx> > Date: Fri Dec 8 15:56:07 2006 +0100 > > [S390] Virtual memmap for s390. > > This is confusing. Is HOLES_IN_ZONE only required when virtual mmap > is being used? If so, why is that? This is a very poorly documented > flag, and I'm saying this after pouring over every commit referencing > it. I should have split that into two commits back then. When writing the vmemmap code for s390 I realized that we never guaranteed that zones start on a MAX_ORDER boundary or have a size that is a multiple of MAX_ORDER. So I just added HOLES_IN_ZONE. > Later this HOLES_IN_ZONE requirement was removed on s390 by commit: > > commit 9f4b0ba81f158df459fa2cfc98ab1475c090f29c > Author: Heiko Carstens <heiko.carstens@xxxxxxxxxx> > Date: Sat Jan 26 14:11:02 2008 +0100 > > [S390] Get rid of HOLES_IN_ZONE requirement. This just made sure that all zones start on a MAX_ORDER boundary and just leaves memory that doesn't fit unused. So the requirement for HOLES_IN_ZONE went away. Later I reduced MAX_ORDER to 9 on s390, so we don't leave large portions of memory unused. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
