x86: mm: Use 2GB memory block size on large-memory x86-64 systems

dblueman · KAGA-KOKO · commit bdee237c0343 · 2014-11-04T18:19:27.000+01:00
On large-memory x86-64 systems of 64GB or more with memory hot-plug enabled, use a 2GB memory block size. Eg with 64GB memory, this reduces the number of directories in /sys/devices/system/memory from 512 to 32, making it more manageable, and reducing the creation time accordingly. This caveat is that the memory can't be offlined (for hotplug or otherwise) with the finer default 128MB granularity, but this is unimportant due to the high memory densities generally used with such large-memory systems, where eg a single DIMM is the order of 16GB. Signed-off-by: Daniel J Blueman <daniel@numascale.com> Cc: Steffen Persvold <sp@numascale.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Link: http://lkml.kernel.org/r/1415089784-28779-4-git-send-email-daniel@numascale.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
@@ -52,7 +52,6 @@
 #include <asm/numa.h>
 #include <asm/cacheflush.h>
 #include <asm/init.h>
-#include <asm/uv/uv.h>
 #include <asm/setup.h>
 
 #include "mm_internal.h"
@@ -1247,12 +1246,10 @@ static unsigned long probe_memory_block_size(void)
 	/* start from 2g */
 	unsigned long bz = 1UL<<31;
 
-#ifdef CONFIG_X86_UV
-	if (is_uv_system()) {
-		printk(KERN_INFO "UV: memory block size 2GB\n");
+	if (totalram_pages >= (64ULL << (30 - PAGE_SHIFT))) {
+		pr_info("Using 2GB memory block size for large-memory system\n");
 		return 2UL * 1024 * 1024 * 1024;
 	}
-#endif
 
 	/* less than 64g installed */
 	if ((max_pfn << PAGE_SHIFT) < (16UL << 32))
