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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kcopyd.h
/*
* Copyright (C) 2001 Sistina Software
*
* This file is released under the GPL.
*
* Kcopyd provides a simple interface for copying an area of one
* block-device to one or more other block-devices, with an asynchronous
* completion notification.
*/
#ifndef DM_KCOPYD_H
#define DM_KCOPYD_H
#include "dm-io.h"
/* FIXME: make this configurable */
#define KCOPYD_MAX_REGIONS 8
#define KCOPYD_IGNORE_ERROR 1
/*
* To use kcopyd you must first create a kcopyd client object.
*/
struct kcopyd_client;
int kcopyd_client_create(unsigned int num_pages, struct kcopyd_client **result);
void kcopyd_client_destroy(struct kcopyd_client *kc);
/*
* Submit a copy job to kcopyd. This is built on top of the
* previous three fns.
*
* read_err is a boolean,
* write_err is a bitset, with 1 bit for each destination region
*/
typedef void (*kcopyd_notify_fn)(int read_err,
unsigned int write_err, void *context);
int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from,
unsigned int num_dests, struct io_region *dests,
unsigned int flags, kcopyd_notify_fn fn, void *context);
#endif
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