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289016f2d1
- Limit the total number of pipes so that we do not exhaust all vm objects in the kernel map. When this limit is reached, a ratelimited message will be printed to the console. - Put a soft limit on the amount of memory consumable by pipes. Once the limit has been reached, all new pipes will be limited to 4K in size, rather than the default of 16K. - Put a limit on the number of pages that may be used for high speed page flipping in order to reduce the amount of wired memory. Pipe writes that occur while this limit is exceeded will fall back to non-page flipping mode. The above values are auto-tuned in subr_param.c and are scaled to take into account both the size of physical memory and the size of the kernel map. These limits help to reduce the "kernel resources exhausted" panics that could be caused by opening a large number of pipes. (Pipes alone are no longer able to exhaust all resources, but other kernel memory hogs in league with pipes may still be able to do so.) PR: 53627 Ideas / comments from: hsu, tjr, dillon@apollo.backplane.com MFC after: 1 week
131 lines
4.2 KiB
C
131 lines
4.2 KiB
C
/*
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* Copyright (c) 1996 John S. Dyson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice immediately at the beginning of the file, without modification,
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* this list of conditions, and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Absolutely no warranty of function or purpose is made by the author
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* John S. Dyson.
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* 4. This work was done expressly for inclusion into FreeBSD. Other use
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* is allowed if this notation is included.
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* 5. Modifications may be freely made to this file if the above conditions
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* are met.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_PIPE_H_
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#define _SYS_PIPE_H_
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#ifndef _KERNEL
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#include <sys/time.h> /* for struct timespec */
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#include <sys/selinfo.h> /* for struct selinfo */
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#include <vm/vm.h> /* for vm_page_t */
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#include <sys/_label.h> /* for struct label */
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#include <machine/param.h> /* for PAGE_SIZE */
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#endif
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/*
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* Pipe buffer size, keep moderate in value, pipes take kva space.
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*/
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#ifndef PIPE_SIZE
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#define PIPE_SIZE 16384
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#endif
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#ifndef BIG_PIPE_SIZE
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#define BIG_PIPE_SIZE (64*1024)
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#endif
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#ifndef SMALL_PIPE_SIZE
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#define SMALL_PIPE_SIZE 4096
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#endif
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/*
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* PIPE_MINDIRECT MUST be smaller than PIPE_SIZE and MUST be bigger
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* than PIPE_BUF.
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*/
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#ifndef PIPE_MINDIRECT
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#define PIPE_MINDIRECT 8192
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#endif
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#define PIPENPAGES (BIG_PIPE_SIZE / PAGE_SIZE + 1)
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/*
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* See sys_pipe.c for info on what these limits mean.
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*/
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extern int maxpipes;
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extern int maxpipekva;
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extern int maxpipekvawired;
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/*
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* Pipe buffer information.
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* Separate in, out, cnt are used to simplify calculations.
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* Buffered write is active when the buffer.cnt field is set.
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*/
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struct pipebuf {
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u_int cnt; /* number of chars currently in buffer */
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u_int in; /* in pointer */
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u_int out; /* out pointer */
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u_int size; /* size of buffer */
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caddr_t buffer; /* kva of buffer */
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struct vm_object *object; /* VM object containing buffer */
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};
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/*
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* Information to support direct transfers between processes for pipes.
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*/
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struct pipemapping {
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vm_offset_t kva; /* kernel virtual address */
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vm_size_t cnt; /* number of chars in buffer */
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vm_size_t pos; /* current position of transfer */
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int npages; /* number of pages */
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vm_page_t ms[PIPENPAGES]; /* pages in source process */
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};
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/*
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* Bits in pipe_state.
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*/
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#define PIPE_ASYNC 0x004 /* Async? I/O. */
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#define PIPE_WANTR 0x008 /* Reader wants some characters. */
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#define PIPE_WANTW 0x010 /* Writer wants space to put characters. */
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#define PIPE_WANT 0x020 /* Pipe is wanted to be run-down. */
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#define PIPE_SEL 0x040 /* Pipe has a select active. */
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#define PIPE_EOF 0x080 /* Pipe is in EOF condition. */
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#define PIPE_LOCKFL 0x100 /* Process has exclusive access to pointers/data. */
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#define PIPE_LWANT 0x200 /* Process wants exclusive access to pointers/data. */
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#define PIPE_DIRECTW 0x400 /* Pipe direct write active. */
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#define PIPE_DIRECTOK 0x800 /* Direct mode ok. */
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/*
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* Per-pipe data structure.
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* Two of these are linked together to produce bi-directional pipes.
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*/
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struct pipe {
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struct pipebuf pipe_buffer; /* data storage */
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struct pipemapping pipe_map; /* pipe mapping for direct I/O */
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struct selinfo pipe_sel; /* for compat with select */
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struct timespec pipe_atime; /* time of last access */
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struct timespec pipe_mtime; /* time of last modify */
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struct timespec pipe_ctime; /* time of status change */
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struct sigio *pipe_sigio; /* information for async I/O */
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struct pipe *pipe_peer; /* link with other direction */
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u_int pipe_state; /* pipe status info */
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int pipe_busy; /* busy flag, mostly to handle rundown sanely */
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struct label *pipe_label; /* pipe MAC label - shared */
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struct mtx *pipe_mtxp; /* shared mutex between both pipes */
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};
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#define PIPE_MTX(pipe) (pipe)->pipe_mtxp
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#define PIPE_LOCK(pipe) mtx_lock(PIPE_MTX(pipe))
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#define PIPE_UNLOCK(pipe) mtx_unlock(PIPE_MTX(pipe))
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#define PIPE_LOCK_ASSERT(pipe, type) mtx_assert(PIPE_MTX(pipe), (type))
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#endif /* !_SYS_PIPE_H_ */
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