[v4,14/15] mm: optimize early system hash allocations

Clients can call alloc_large_system_hash() with flag: HASH_ZERO to specify
that memory that was allocated for system hash needs to be zeroed,
otherwise the memory does not need to be zeroed, and client will initialize
it.

If memory does not need to be zero'd, call the new
memblock_virt_alloc_raw() interface, and thus improve the boot performance.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
---
 mm/page_alloc.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

Hi Pavel,

[auto build test ERROR on mmotm/master]
[also build test ERROR on v4.13-rc3]
[cannot apply to next-20170802]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Pavel-Tatashin/complete-deferred-page-initialization/20170803-081025
base:   git://git.cmpxchg.org/linux-mmotm.git master
config: mips-allmodconfig (attached as .config)
compiler: mips-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mips 

All error/warnings (new ones prefixed by >>):

   mm/page_alloc.c: In function 'alloc_large_system_hash':
>> mm/page_alloc.c:7369:13: error: implicit declaration of function 'memblock_virt_alloc_raw' [-Werror=implicit-function-declaration]
        table = memblock_virt_alloc_raw(size, 0);
                ^~~~~~~~~~~~~~~~~~~~~~~
>> mm/page_alloc.c:7369:11: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
        table = memblock_virt_alloc_raw(size, 0);
              ^
   cc1: some warnings being treated as errors

vim +/memblock_virt_alloc_raw +7369 mm/page_alloc.c

  7328	
  7329			/* limit to 1 bucket per 2^scale bytes of low memory */
  7330			if (scale > PAGE_SHIFT)
  7331				numentries >>= (scale - PAGE_SHIFT);
  7332			else
  7333				numentries <<= (PAGE_SHIFT - scale);
  7334	
  7335			/* Make sure we've got at least a 0-order allocation.. */
  7336			if (unlikely(flags & HASH_SMALL)) {
  7337				/* Makes no sense without HASH_EARLY */
  7338				WARN_ON(!(flags & HASH_EARLY));
  7339				if (!(numentries >> *_hash_shift)) {
  7340					numentries = 1UL << *_hash_shift;
  7341					BUG_ON(!numentries);
  7342				}
  7343			} else if (unlikely((numentries * bucketsize) < PAGE_SIZE))
  7344				numentries = PAGE_SIZE / bucketsize;
  7345		}
  7346		numentries = roundup_pow_of_two(numentries);
  7347	
  7348		/* limit allocation size to 1/16 total memory by default */
  7349		if (max == 0) {
  7350			max = ((unsigned long long)nr_all_pages << PAGE_SHIFT) >> 4;
  7351			do_div(max, bucketsize);
  7352		}
  7353		max = min(max, 0x80000000ULL);
  7354	
  7355		if (numentries < low_limit)
  7356			numentries = low_limit;
  7357		if (numentries > max)
  7358			numentries = max;
  7359	
  7360		log2qty = ilog2(numentries);
  7361	
  7362		gfp_flags = (flags & HASH_ZERO) ? GFP_ATOMIC | __GFP_ZERO : GFP_ATOMIC;
  7363		do {
  7364			size = bucketsize << log2qty;
  7365			if (flags & HASH_EARLY) {
  7366				if (flags & HASH_ZERO)
  7367					table = memblock_virt_alloc_nopanic(size, 0);
  7368				else
> 7369					table = memblock_virt_alloc_raw(size, 0);
  7370			} else if (hashdist) {
  7371				table = __vmalloc(size, gfp_flags, PAGE_KERNEL);
  7372			} else {
  7373				/*
  7374				 * If bucketsize is not a power-of-two, we may free
  7375				 * some pages at the end of hash table which
  7376				 * alloc_pages_exact() automatically does
  7377				 */
  7378				if (get_order(size) < MAX_ORDER) {
  7379					table = alloc_pages_exact(size, gfp_flags);
  7380					kmemleak_alloc(table, size, 1, gfp_flags);
  7381				}
  7382			}
  7383		} while (!table && size > PAGE_SIZE && --log2qty);
  7384	
  7385		if (!table)
  7386			panic("Failed to allocate %s hash table\n", tablename);
  7387	
  7388		pr_info("%s hash table entries: %ld (order: %d, %lu bytes)\n",
  7389			tablename, 1UL << log2qty, ilog2(size) - PAGE_SHIFT, size);
  7390	
  7391		if (_hash_shift)
  7392			*_hash_shift = log2qty;
  7393		if (_hash_mask)
  7394			*_hash_mask = (1 << log2qty) - 1;
  7395	
  7396		return table;
  7397	}
  7398	

---
0-DAY kernel test infrastructure                Open Source Technology Center
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