Rich Felker
4750cf4202
i did some testing trying to switch malloc to use the new internal lock with priority inheritance, and my malloc contention test got 20-100 times slower. if priority inheritance futexes are this slow, it's simply too high a price to pay for avoiding priority inversion. maybe we can consider them somewhere down the road once the kernel folks get their act together on this (and perferably don't link it to glibc's inefficient lock API)... as such, i've switch __lock to use malloc's implementation of lightweight locks, and updated all the users of the code to use an array with a waiter count for their locks. this should give optimal performance in the vast majority of cases, and it's simple. malloc is still using its own internal copy of the lock code because it seems to yield measurably better performance with -O3 when it's inlined (20% or more difference in the contention stress test).
108 lines
2.5 KiB
C
108 lines
2.5 KiB
C
#ifndef _STDIO_IMPL_H
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#define _STDIO_IMPL_H
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#include <stdio.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <stdarg.h>
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#include <string.h>
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#include <inttypes.h>
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#include <wchar.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <errno.h>
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#include <termios.h>
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#include <sys/ioctl.h>
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#include <ctype.h>
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#include <sys/wait.h>
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#include <math.h>
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#include <float.h>
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#include <sys/uio.h>
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#include "syscall.h"
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#include "libc.h"
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#define UNGET 8
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#define FLOCK(f) int __need_unlock = ((f)->lock>=0 ? __lockfile((f)) : 0)
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#define FUNLOCK(f) if (__need_unlock) __unlockfile((f)); else
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#define F_PERM 1
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#define F_NORD 4
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#define F_NOWR 8
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#define F_EOF 16
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#define F_ERR 32
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#define F_SVB 64
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struct __FILE_s {
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unsigned flags;
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unsigned char *rpos, *rend;
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int (*close)(FILE *);
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unsigned char *wend, *wpos;
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unsigned char *mustbezero_1;
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unsigned char *wbase;
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size_t (*read)(FILE *, unsigned char *, size_t);
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size_t (*write)(FILE *, const unsigned char *, size_t);
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off_t (*seek)(FILE *, off_t, int);
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unsigned char *buf;
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size_t buf_size;
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FILE *prev, *next;
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int fd;
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int pipe_pid;
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long lockcount;
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short dummy3;
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signed char mode;
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signed char lbf;
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int lock;
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int waiters;
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void *cookie;
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off_t off;
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int (*flush)(FILE *);
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void *mustbezero_2;
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unsigned char *shend;
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off_t shlim, shcnt;
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};
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size_t __stdio_read(FILE *, unsigned char *, size_t);
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size_t __stdio_write(FILE *, const unsigned char *, size_t);
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size_t __stdout_write(FILE *, const unsigned char *, size_t);
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off_t __stdio_seek(FILE *, off_t, int);
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int __stdio_close(FILE *);
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size_t __string_read(FILE *, unsigned char *, size_t);
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int __toread(FILE *);
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int __towrite(FILE *);
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int __overflow(FILE *, int);
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int __oflow(FILE *);
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int __uflow(FILE *);
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int __underflow(FILE *);
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int __fseeko(FILE *, off_t, int);
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int __fseeko_unlocked(FILE *, off_t, int);
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off_t __ftello(FILE *);
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off_t __ftello_unlocked(FILE *);
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size_t __fwritex(const unsigned char *, size_t, FILE *);
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int __putc_unlocked(int, FILE *);
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FILE *__fdopen(int, const char *);
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#define OFLLOCK() LOCK(libc.ofl_lock)
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#define OFLUNLOCK() UNLOCK(libc.ofl_lock)
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#define feof(f) ((f)->flags & F_EOF)
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#define ferror(f) ((f)->flags & F_ERR)
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#define getc_unlocked(f) \
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( ((f)->rpos < (f)->rend) ? *(f)->rpos++ : __uflow((f)) )
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#define putc_unlocked(c, f) ( ((c)!=(f)->lbf && (f)->wpos<(f)->wend) \
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? *(f)->wpos++ = (c) : __overflow((f),(c)) )
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/* Caller-allocated FILE * operations */
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FILE *__fopen_rb_ca(const char *, FILE *, unsigned char *, size_t);
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int __fclose_ca(FILE *);
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#endif
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