Revision dda50e716dc9451f40eebfb2902c260e4f62cf34 authored by Andi Kleen on 17 May 2005, 04:53:25 UTC, committed by Linus Torvalds on 17 May 2005, 14:59:14 UTC
The new TSC sync algorithm recently submitted did not work too well. The result was that some MP machines where the TSC came up of the BIOS very unsynchronized and that did not have HPET support were nearly unusable because the time would jump forwards and backwards between CPUs. After a lot of research ;-) and some more prototypes I ended up with just using the one from IA64 which looks best. It has some internal self tuning that should adapt to changing interconnect latencies. It holds up in my tests so far. I believe it was originally written by David Mosberger, I just ported it over to x86-64. See the inline comment for a description. This cleans up the code because it uses smp_call_function for syncing instead of having custom hooks in SMP bootup. Please note that the cycle numbers it outputs are too optimistic because they do not take into account the latency of WRMSR and RDTSC, which can be hundreds of cycles. It seems to be able to sync a dual Opteron to 200-300 cycles, which is probably good enough. There is a timing window during AP bootup where interrupts can see inconsistent time before the TSC is synced. It is hard to avoid unfortunately because we can only do the TSC sync after some setup, and we need to enable interrupts before that. I just ignored it for now. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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raid6.h
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright 2003 H. Peter Anvin - All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
* Bostom MA 02111-1307, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
#ifndef LINUX_RAID_RAID6_H
#define LINUX_RAID_RAID6_H
#ifdef __KERNEL__
/* Set to 1 to use kernel-wide empty_zero_page */
#define RAID6_USE_EMPTY_ZERO_PAGE 0
#include <linux/module.h>
#include <linux/stddef.h>
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mempool.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/raid/md.h>
#include <linux/raid/raid5.h>
typedef raid5_conf_t raid6_conf_t; /* Same configuration */
/* Additional compute_parity mode -- updates the parity w/o LOCKING */
#define UPDATE_PARITY 4
/* We need a pre-zeroed page... if we don't want to use the kernel-provided
one define it here */
#if RAID6_USE_EMPTY_ZERO_PAGE
# define raid6_empty_zero_page empty_zero_page
#else
extern const char raid6_empty_zero_page[PAGE_SIZE];
#endif
#else /* ! __KERNEL__ */
/* Used for testing in user space */
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <stddef.h>
#include <sys/mman.h>
#include <sys/types.h>
/* Not standard, but glibc defines it */
#define BITS_PER_LONG __WORDSIZE
typedef uint8_t u8;
typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;
#ifndef PAGE_SIZE
# define PAGE_SIZE 4096
#endif
extern const char raid6_empty_zero_page[PAGE_SIZE];
#define __init
#define __exit
#define __attribute_const__ __attribute__((const))
#define preempt_enable()
#define preempt_disable()
#endif /* __KERNEL__ */
/* Routine choices */
struct raid6_calls {
void (*gen_syndrome)(int, size_t, void **);
int (*valid)(void); /* Returns 1 if this routine set is usable */
const char *name; /* Name of this routine set */
int prefer; /* Has special performance attribute */
};
/* Selected algorithm */
extern struct raid6_calls raid6_call;
/* Algorithm list */
extern const struct raid6_calls * const raid6_algos[];
int raid6_select_algo(void);
/* Return values from chk_syndrome */
#define RAID6_OK 0
#define RAID6_P_BAD 1
#define RAID6_Q_BAD 2
#define RAID6_PQ_BAD 3
/* Galois field tables */
extern const u8 raid6_gfmul[256][256] __attribute__((aligned(256)));
extern const u8 raid6_gfexp[256] __attribute__((aligned(256)));
extern const u8 raid6_gfinv[256] __attribute__((aligned(256)));
extern const u8 raid6_gfexi[256] __attribute__((aligned(256)));
/* Recovery routines */
void raid6_2data_recov(int disks, size_t bytes, int faila, int failb, void **ptrs);
void raid6_datap_recov(int disks, size_t bytes, int faila, void **ptrs);
void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, void **ptrs);
/* Some definitions to allow code to be compiled for testing in userspace */
#ifndef __KERNEL__
# define jiffies raid6_jiffies()
# define printk printf
# define GFP_KERNEL 0
# define __get_free_pages(x,y) ((unsigned long)mmap(NULL, PAGE_SIZE << (y), PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0))
# define free_pages(x,y) munmap((void *)(x), (y)*PAGE_SIZE)
static inline void cpu_relax(void)
{
/* Nothing */
}
#undef HZ
#define HZ 1000
static inline uint32_t raid6_jiffies(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec*1000 + tv.tv_usec/1000;
}
#endif /* ! __KERNEL__ */
#endif /* LINUX_RAID_RAID6_H */
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