Christoph Lameter b263295dbf x86: 64-bit, make sparsemem vmemmap the only memory model ... Use sparsemem as the only memory model for UP, SMP and NUMA. Measurements indicate that DISCONTIGMEM has a higher overhead than sparsemem. And FLATMEMs benefits are minimal. So I think its best to simply standardize on sparsemem. Results of page allocator tests (test can be had via git from slab git tree branch tests) Measurements in cycle counts. 1000 allocations were performed and then the average cycle count was calculated. Order FlatMem Discontig SparseMem 0 639 665 641 1 567 647 593 2 679 774 692 3 763 967 781 4 961 1501 962 5 1356 2344 1392 6 2224 3982 2336 7 4869 7225 5074 8 12500 14048 12732 9 27926 28223 28165 10 58578 58714 58682 (Note that FlatMem is an SMP config and the rest NUMA configurations) Memory use: SMP Sparsemem ------------- Kernel size: text data bss dec hex filename 3849268 397739 1264856 5511863 541ab7 vmlinux total used free shared buffers cached Mem: 8242252 41164 8201088 0 352 11512 -/+ buffers/cache: 29300 8212952 Swap: 9775512 0 9775512 SMP Flatmem ----------- Kernel size: text data bss dec hex filename 3844612 397739 1264536 5506887 540747 vmlinux So 4.5k growth in text size vs. FLATMEM. total used free shared buffers cached Mem: 8244052 40544 8203508 0 352 11484 -/+ buffers/cache: 28708 8215344 2k growth in overall memory use after boot. NUMA discontig: text data bss dec hex filename 3888124 470659 1276504 5635287 55fcd7 vmlinux total used free shared buffers cached Mem: 8256256 56908 8199348 0 352 11496 -/+ buffers/cache: 45060 8211196 Swap: 9775512 0 9775512 NUMA sparse: text data bss dec hex filename 3896428 470659 1276824 5643911 561e87 vmlinux 8k text growth. Given that we fully inline virt_to_page and friends now that is rather good. total used free shared buffers cached Mem: 8264720 57240 8207480 0 352 11516 -/+ buffers/cache: 45372 8219348 Swap: 9775512 0 9775512 The total available memory is increased by 8k. This patch makes sparsemem the default and removes discontig and flatmem support from x86. [ akpm@linux-foundation.org: allnoconfig build fix ] Acked-by: Andi Kleen <ak@suse.de> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>		2008-01-30 13:30:47 +01:00
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i386_defconfig	…
x86_64_defconfig	x86: 64-bit, make sparsemem vmemmap the only memory model	2008-01-30 13:30:47 +01:00