File:  [DragonFly] / src / sys / sys / pipe.h
Revision 1.4: download - view: text, annotated - select for diffs
Sun Mar 28 08:25:46 2004 UTC (10 years, 8 months ago) by dillon
Branches: MAIN
CVS tags: HEAD
Import Alan Cox's /usr/src/sys/kern/sys_pipe.c 1.171.  This rips out
writer-side KVA mappings and replaces them with writer-side vm_page wiring
(left intact from before) plus reader-side SF_BUF copies.

Import 1.141, which is a simple patch which removes a blocking condition
when space is available in the pipe's write buffer which was causing
non-blocking I/O select-based writes to spin-wait unnecessarily.  1.171
rips out writer-side KVA mappings and replaces them

Import FreeBSD-5.x's uiomove_fromphys(), which sys_pipe.c now uses.  This
procedure could become very useful in a number of DragonFly subsystems.

This greatly improves PIPE performance for the direct-mapped case (moderate
to large reads and writes).  Additionally, recent scheduler fixes greatly
improve PIPE performance for both the direct-mapped and small-buffer cases.

NOTE: wired page limits for pipes have not yet been imported, and the heavy
use of sf_buf's may require some tuning in the many-pipes case.


    BLKSIZE	BEFORE		AFTER
		MBytes/s	MBytes/s	Tests on AMD64/3200+ FN85 MB
    -------	------		------		(64KB L1, 1MB L2)
    256KB	1900		2200
     64KB	1800		2200
     16KB	1650		2500-3000
      8KB	1400		2300
      4KB	1300		1400-1500	(note 1)

    note 1: The 4KB case is not a direct-write case, the results are due to
    the scheduler fixes only.


Obtained-from: FreeBSD-5.x / FreeBSD's Alan Cox

    1: /*
    2:  * Copyright (c) 1996 John S. Dyson
    3:  * All rights reserved.
    4:  *
    5:  * Redistribution and use in source and binary forms, with or without
    6:  * modification, are permitted provided that the following conditions
    7:  * are met:
    8:  * 1. Redistributions of source code must retain the above copyright
    9:  *    notice immediately at the beginning of the file, without modification,
   10:  *    this list of conditions, and the following disclaimer.
   11:  * 2. Redistributions in binary form must reproduce the above copyright
   12:  *    notice, this list of conditions and the following disclaimer in the
   13:  *    documentation and/or other materials provided with the distribution.
   14:  * 3. Absolutely no warranty of function or purpose is made by the author
   15:  *    John S. Dyson.
   16:  * 4. This work was done expressly for inclusion into FreeBSD.  Other use
   17:  *    is allowed if this notation is included.
   18:  * 5. Modifications may be freely made to this file if the above conditions
   19:  *    are met.
   20:  *
   21:  * $FreeBSD: src/sys/sys/pipe.h,v 1.16 1999/12/29 04:24:45 peter Exp $
   22:  * $DragonFly: src/sys/sys/pipe.h,v 1.4 2004/03/28 08:25:46 dillon Exp $
   23:  */
   24: 
   25: #ifndef _SYS_PIPE_H_
   26: #define _SYS_PIPE_H_
   27: 
   28: #ifndef _KERNEL
   29: #include <sys/time.h>			/* for struct timespec */
   30: #include <sys/select.h>			/* for struct selinfo */
   31: #include <vm/vm.h>			/* for vm_page_t */
   32: #include <machine/param.h>		/* for PAGE_SIZE */
   33: #endif
   34: 
   35: /*
   36:  * Pipe buffer size, keep moderate in value, pipes take kva space.
   37:  */
   38: #ifndef PIPE_SIZE
   39: #define PIPE_SIZE	16384
   40: #endif
   41: 
   42: #ifndef BIG_PIPE_SIZE
   43: #define BIG_PIPE_SIZE	(64*1024)
   44: #endif
   45: 
   46: /*
   47:  * PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
   48:  * than PIPE_BUF.
   49:  */
   50: #ifndef PIPE_MINDIRECT
   51: #define PIPE_MINDIRECT	8192
   52: #endif
   53: 
   54: #define PIPENPAGES	(BIG_PIPE_SIZE / PAGE_SIZE + 1)
   55: 
   56: /*
   57:  * Pipe buffer information.
   58:  * Separate in, out, cnt are used to simplify calculations.
   59:  * Buffered write is active when the buffer.cnt field is set.
   60:  */
   61: struct pipebuf {
   62: 	u_int	cnt;		/* number of chars currently in buffer */
   63: 	u_int	in;		/* in pointer */
   64: 	u_int	out;		/* out pointer */
   65: 	u_int	size;		/* size of buffer */
   66: 	caddr_t	buffer;		/* kva of buffer */
   67: 	struct  vm_object *object;	/* VM object containing buffer */
   68: };
   69: 
   70: /*
   71:  * Information to support direct transfers between processes for pipes.
   72:  */
   73: struct pipemapping {
   74: 	vm_size_t	cnt;		/* number of chars in buffer */
   75: 	vm_size_t	pos;		/* current position of transfer */
   76: 	int		npages;		/* number of pages */
   77: 	vm_page_t	ms[PIPENPAGES];	/* pages in source process */
   78: };
   79: 
   80: /*
   81:  * Bits in pipe_state.
   82:  */
   83: #define PIPE_ASYNC	0x004	/* Async? I/O. */
   84: #define PIPE_WANTR	0x008	/* Reader wants some characters. */
   85: #define PIPE_WANTW	0x010	/* Writer wants space to put characters. */
   86: #define PIPE_WANT	0x020	/* Pipe is wanted to be run-down. */
   87: #define PIPE_SEL	0x040	/* Pipe has a select active. */
   88: #define PIPE_EOF	0x080	/* Pipe is in EOF condition. */
   89: #define PIPE_LOCK	0x100	/* Process has exclusive access to pointers/data. */
   90: #define PIPE_LWANT	0x200	/* Process wants exclusive access to pointers/data. */
   91: #define PIPE_DIRECTW	0x400	/* Pipe direct write active. */
   92: #define PIPE_DIRECTOK	0x800	/* Direct mode ok. */
   93: 
   94: /*
   95:  * Per-pipe data structure.
   96:  * Two of these are linked together to produce bi-directional pipes.
   97:  */
   98: struct pipe {
   99: 	struct	pipebuf pipe_buffer;	/* data storage */
  100: 	struct	pipemapping pipe_map;	/* pipe mapping for direct I/O */
  101: 	struct	selinfo pipe_sel;	/* for compat with select */
  102: 	struct	timespec pipe_atime;	/* time of last access */
  103: 	struct	timespec pipe_mtime;	/* time of last modify */
  104: 	struct	timespec pipe_ctime;	/* time of status change */
  105: 	struct	sigio *pipe_sigio;	/* information for async I/O */
  106: 	struct	pipe *pipe_peer;	/* link with other direction */
  107: 	u_int	pipe_state;		/* pipe status info */
  108: 	int	pipe_busy;		/* busy flag, mostly to handle rundown sanely */
  109: };
  110: 
  111: #endif /* !_SYS_PIPE_H_ */