1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. 23 */ 24 25 .file "smt_pause.s" 26 27#include <sys/asm_linkage.h> 28#include <../assym.h> 29#include <sys/stack.h> 30 31/* 32 * void smt_pause(void) 33 * 34 * Do nothing efficiently. 35 * We do the dance with the lwpid so that the actual address is spread 36 * across cache banks thus avoiding hot spots. 37 * Casx arguments are a no-op, but they force access to L2 cache, which 38 * takes lots of cycles. 39 */ 40 41#ifdef lint 42void 43smt_pause(void) 44{ 45} 46#else 47#define BANKS (4 * 64) /* covers 4 cachelines, all banks */ 48 ENTRY(smt_pause) 49 save %sp, -SA(MINFRAME+BANKS), %sp 50 ld [%g7 + UL_LWPID], %i5 51 add %fp, STACK_BIAS-BANKS, %i3 52 and %i5, 0x3, %i4 ! save last 2 bits 53 sll %i4, 0x6, %i2 ! pick a slot 54 add %i2, %i3, %o0 55 casx [%o0], %g0, %g0 56 casx [%o0], %g0, %g0 57 ret 58 restore 59 SET_SIZE(smt_pause) 60#endif 61