Hi, On Monday, 23 July 2007 15:05, Nigel Cunningham wrote: > Hi all. > > As we all know, pageflags have been a scarce resource for a while now. These > patches seek to help address that issue by adding support for a new type > of 'dynamically allocated' pageflag. > > The basic idea is that we use per node & zone bitmaps built out of order zero > allocations, to replace bits in page->flags. Bitmaps can be sparse, being > populated when a bit on the page is set, and returning zero for all bits in > sparse pages. Untested hotplug support is included. > > This method of storing the data does of course come with a performance hit. > I've included some simple timing loops in #ifdef'd code that help quantify > that. > > Interestingly, the new implementation is actually quicker under some > circumstances. In cases where the usage pattern involves operating on the > flags for a number of pages in succession, the hit involved in getting the > struct pages from main memory appears to be greater than that involved in > calculating which unsigned long and bit to test. > > Tested only on UP (x86_64) so far.
How does it compare to the memory bitmaps used by swsusp, defined in kernel/power/snapshot.c? Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
