d3f54e81dd
* User allocates ZFOD region, but does not actually touch the buffer to fault in the pages. * In a loop, user writes this buffer to a network socket, triggering sosend_loan(). * uvm_loan() calls uvm_loanzero() once for each page in the loaned region (since the pages have not yet faulted in). This causes a page to be allocated and zero'd. The result is the kernel spends a lot of time allocating and zero'ing pages. This fixes creates a special object which owns a single zero'd page. This single zero'd page is used to satisfy all loans of non-resident ZFOD mappings. Thanks to Allen Briggs for discovering the problem and for providing an initial patch.
60 lines
2.2 KiB
C
60 lines
2.2 KiB
C
/* $NetBSD: uvm_loan.h,v 1.10 2003/03/04 06:18:54 thorpej Exp $ */
|
|
|
|
/*
|
|
*
|
|
* Copyright (c) 1997 Charles D. Cranor and Washington University.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by Charles D. Cranor and
|
|
* Washington University.
|
|
* 4. The name of the author may not be used to endorse or promote products
|
|
* derived from this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
* from: Id: uvm_loan.h,v 1.1.4.1 1997/12/08 16:07:14 chuck Exp
|
|
*/
|
|
|
|
#ifndef _UVM_UVM_LOAN_H_
|
|
#define _UVM_UVM_LOAN_H_
|
|
|
|
#ifdef _KERNEL
|
|
|
|
/*
|
|
* flags for uvm_loan()
|
|
*/
|
|
|
|
#define UVM_LOAN_TOANON 0x1 /* loan to anon */
|
|
#define UVM_LOAN_TOPAGE 0x2 /* loan to page */
|
|
|
|
/*
|
|
* loan prototypes
|
|
*/
|
|
|
|
void uvm_loan_init __P((void));
|
|
int uvm_loan __P((struct vm_map *, vaddr_t, vsize_t, void *, int));
|
|
void uvm_unloan __P((void *, int, int));
|
|
|
|
#endif /* _KERNEL */
|
|
|
|
#endif /* _UVM_UVM_LOAN_H_ */
|