On Fri, 5 Feb 2010, Mel Gorman wrote: > > > + /* > > > + * Index should be a value between 0 and 1. Return a value to 3 > > > + * decimal places. > > > + * > > > + * 0 => no fragmentation > > > + * 1 => high fragmentation > > > + */ > > > + return ((info->free_pages - (info->free_blocks_suitable << order)) * 1000) / info->free_pages; > > > + > > > > This value is only for userspace consumption via /proc/pagetypeinfo, so > > I'm wondering why it needs to be exported as an index. Other than a loss > > of precision, wouldn't this be easier to understand (especially when > > coupled with the free page counts already exported) if it were multipled > > by 100 rather than 1000 and shown as a percent of _usable_ free memory at > > each order? > > I find it easier to understand either way, but that's hardly a surprise. > The 1000 is because of the loss of precision. I can make it a 100 but I > don't think it makes much of a difference. > This suggestion was coupled with the subsequent note that there is no documentation of what "unusuable free space index" is, except by the implementation itself. Since the value isn't used by the kernel, I think exporting the value as a percent would be easier understood by the user without looking up the semantics. I don't have strong feelings either way, however. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>