1*5d9d9091SRichard Lowe/* 2*5d9d9091SRichard Lowe * CDDL HEADER START 3*5d9d9091SRichard Lowe * 4*5d9d9091SRichard Lowe * The contents of this file are subject to the terms of the 5*5d9d9091SRichard Lowe * Common Development and Distribution License (the "License"). 6*5d9d9091SRichard Lowe * You may not use this file except in compliance with the License. 7*5d9d9091SRichard Lowe * 8*5d9d9091SRichard Lowe * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9*5d9d9091SRichard Lowe * or http://www.opensolaris.org/os/licensing. 10*5d9d9091SRichard Lowe * See the License for the specific language governing permissions 11*5d9d9091SRichard Lowe * and limitations under the License. 12*5d9d9091SRichard Lowe * 13*5d9d9091SRichard Lowe * When distributing Covered Code, include this CDDL HEADER in each 14*5d9d9091SRichard Lowe * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15*5d9d9091SRichard Lowe * If applicable, add the following below this CDDL HEADER, with the 16*5d9d9091SRichard Lowe * fields enclosed by brackets "[]" replaced with your own identifying 17*5d9d9091SRichard Lowe * information: Portions Copyright [yyyy] [name of copyright owner] 18*5d9d9091SRichard Lowe * 19*5d9d9091SRichard Lowe * CDDL HEADER END 20*5d9d9091SRichard Lowe */ 21*5d9d9091SRichard Lowe/* 22*5d9d9091SRichard Lowe * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. 23*5d9d9091SRichard Lowe */ 24*5d9d9091SRichard Lowe 25*5d9d9091SRichard Lowe .file "smt_pause.s" 26*5d9d9091SRichard Lowe 27*5d9d9091SRichard Lowe#include <sys/asm_linkage.h> 28*5d9d9091SRichard Lowe#include <../assym.h> 29*5d9d9091SRichard Lowe#include <sys/stack.h> 30*5d9d9091SRichard Lowe 31*5d9d9091SRichard Lowe/* 32*5d9d9091SRichard Lowe * void smt_pause(void) 33*5d9d9091SRichard Lowe * 34*5d9d9091SRichard Lowe * Do nothing efficiently. 35*5d9d9091SRichard Lowe * We do the dance with the lwpid so that the actual address is spread 36*5d9d9091SRichard Lowe * across cache banks thus avoiding hot spots. 37*5d9d9091SRichard Lowe * Casx arguments are a no-op, but they force access to L2 cache, which 38*5d9d9091SRichard Lowe * takes lots of cycles. 39*5d9d9091SRichard Lowe */ 40*5d9d9091SRichard Lowe 41*5d9d9091SRichard Lowe#ifdef lint 42*5d9d9091SRichard Lowevoid 43*5d9d9091SRichard Lowesmt_pause(void) 44*5d9d9091SRichard Lowe{ 45*5d9d9091SRichard Lowe} 46*5d9d9091SRichard Lowe#else 47*5d9d9091SRichard Lowe#define BANKS (4 * 64) /* covers 4 cachelines, all banks */ 48*5d9d9091SRichard Lowe ENTRY(smt_pause) 49*5d9d9091SRichard Lowe save %sp, -SA(MINFRAME+BANKS), %sp 50*5d9d9091SRichard Lowe ld [%g7 + UL_LWPID], %i5 51*5d9d9091SRichard Lowe add %fp, STACK_BIAS-BANKS, %i3 52*5d9d9091SRichard Lowe and %i5, 0x3, %i4 ! save last 2 bits 53*5d9d9091SRichard Lowe sll %i4, 0x6, %i2 ! pick a slot 54*5d9d9091SRichard Lowe add %i2, %i3, %o0 55*5d9d9091SRichard Lowe casx [%o0], %g0, %g0 56*5d9d9091SRichard Lowe casx [%o0], %g0, %g0 57*5d9d9091SRichard Lowe ret 58*5d9d9091SRichard Lowe restore 59*5d9d9091SRichard Lowe SET_SIZE(smt_pause) 60*5d9d9091SRichard Lowe#endif 61