1221828Sgrehan/* 2221828Sgrehan * Copyright 2009-2015 Samy Al Bahra. 3221828Sgrehan * All rights reserved. 4221828Sgrehan * 5221828Sgrehan * Redistribution and use in source and binary forms, with or without 6221828Sgrehan * modification, are permitted provided that the following conditions 7221828Sgrehan * are met: 8221828Sgrehan * 1. Redistributions of source code must retain the above copyright 9221828Sgrehan * notice, this list of conditions and the following disclaimer. 10221828Sgrehan * 2. Redistributions in binary form must reproduce the above copyright 11221828Sgrehan * notice, this list of conditions and the following disclaimer in the 12221828Sgrehan * documentation and/or other materials provided with the distribution. 13221828Sgrehan * 14221828Sgrehan * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15221828Sgrehan * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16221828Sgrehan * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17221828Sgrehan * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18221828Sgrehan * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19221828Sgrehan * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20221828Sgrehan * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21221828Sgrehan * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22221828Sgrehan * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23221828Sgrehan * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24221828Sgrehan * SUCH DAMAGE. 25221828Sgrehan */ 26245678Sneel 27221828Sgrehan#ifndef CK_BACKOFF_H 28221828Sgrehan#define CK_BACKOFF_H 29221828Sgrehan 30221828Sgrehan#include <ck_cc.h> 31221828Sgrehan#include <ck_pr.h> 32221828Sgrehan 33221828Sgrehan#ifndef CK_BACKOFF_CEILING 34221828Sgrehan#define CK_BACKOFF_CEILING ((1 << 20) - 1) 35221828Sgrehan#endif 36221828Sgrehan 37221828Sgrehan#define CK_BACKOFF_INITIALIZER (1 << 9) 38221828Sgrehan 39221828Sgrehantypedef unsigned int ck_backoff_t; 40221828Sgrehan 41258579Sneel/* 42258075Sneel * This is a exponential back-off implementation. 43221828Sgrehan */ 44256072SneelCK_CC_INLINE static void 45256072Sneelck_backoff_eb(unsigned int *c) 46256072Sneel{ 47221828Sgrehan unsigned int i, ceiling; 48240922Sneel 49240922Sneel ceiling = *c; 50260466Sneel for (i = 0; i < ceiling; i++) 51221828Sgrehan ck_pr_barrier(); 52259782Sjhb 53256072Sneel *c = ceiling <<= ceiling < CK_BACKOFF_CEILING; 54256072Sneel return; 55260619Sneel} 56221828Sgrehan 57221828Sgrehan#endif /* CK_BACKOFF_H */ 58221828Sgrehan