brain-hackers_pepepper-mirror
/
linux-brain
mirror of https://github.com/brain-hackers/linux-brain.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

x86/mm: Streamline and restore probe_memory_block_size() 

The cumulative effect of the following two commits:

  bdee237c03 ("x86: mm: Use 2GB memory block size on large-memory x86-64 systems")
  982792c782 ("x86, mm: probe memory block size for generic x86 64bit")

... is some pretty convoluted code.

The first commit also removed code for the UV case without stated reason,
which might lead to unexpected change in behavior.

This commit has no other (intended) functional change; just seeks to simplify
and make the code more understandable, beyond restoring the UV behavior.

The whole section with the "tail size" doesn't seem to be
reachable, since both the >= 64GB and < 64GB case return, so it
was removed.

Signed-off-by: Seth Jennings <sjennings@variantweb.net>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1448902063-18885-1-git-send-email-sjennings@variantweb.net
[ Rewrote the title and changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Seth Jennings 2015-11-30 10:47:43 -06:00 committed by Ingo Molnar
parent 10a0c0f059
commit 43c75f933b
1 changed files with 6 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
arch/x86/mm/init_64.c
View File

@ -52,6 +52,7 @@
#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"
@ -1193,26 +1194,13 @@ int kern_addr_valid(unsigned long addr)
static unsigned long probe_memory_block_size(void)
{
/* start from 2g */
unsigned long bz = 1UL<<31;
unsigned long bz = MIN_MEMORY_BLOCK_SIZE;
if (totalram_pages >= (64ULL << (30 - PAGE_SHIFT))) {
pr_info("Using 2GB memory block size for large-memory system\n");
return 2UL * 1024 * 1024 * 1024;
}
/* if system is UV or has 64GB of RAM or more, use large blocks */
if (is_uv_system() || ((max_pfn << PAGE_SHIFT) >= (64UL << 30)))
bz = 2UL << 30; /* 2GB */
/* less than 64g installed */
if ((max_pfn << PAGE_SHIFT) < (16UL << 32))
return MIN_MEMORY_BLOCK_SIZE;
/* get the tail size */
while (bz > MIN_MEMORY_BLOCK_SIZE) {
if (!((max_pfn << PAGE_SHIFT) & (bz - 1)))
break;
bz >>= 1;
}
printk(KERN_DEBUG "memory block size : %ldMB\n", bz >> 20);
pr_info("x86/mm: Memory block size: %ldMB\n", bz >> 20);
return bz;
}