s390/mm: zero page cache synonyms for zEC12 (7919e91b) · Commits · 戴 / test

To avoid cache synonyms on System zEC12 32 independent zero pages are required, one for each combination for bits 2**12 to 2**16 of the virtual address. To avoid wasting too much memory on small virtual systems the number of zero pages is limited to 4 if the memory size is less or equal to 64MB. Signed-off-by:

Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/mm/init.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -63,10 +63,18 @@ static unsigned long __init setup_zero_pages(void)
		break;
		case 0x2097: /* z10 */
		case 0x2098: /* z10 */
		default:
		case 0x2817: /* z196 */
		case 0x2818: /* z196 */
		order = 2;
		break;
		case 0x2827: /* zEC12 */
		default:
		order = 5;
		break;
		}
		/* Limit number of empty zero pages for small memory sizes */
		if (order > 2 && totalram_pages <= 16384)
		order = 2;

		empty_zero_page = __get_free_pages(GFP_KERNEL \| __GFP_ZERO, order);
		if (!empty_zero_page)

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