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>
1 parent 93ef70a
mmc_queue.c
/*
* linux/drivers/mmc/mmc_queue.c
*
* Copyright (C) 2003 Russell King, 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 version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
#include "mmc_queue.h"
#define MMC_QUEUE_EXIT (1 << 0)
#define MMC_QUEUE_SUSPENDED (1 << 1)
/*
* Prepare a MMC request. Essentially, this means passing the
* preparation off to the media driver. The media driver will
* create a mmc_io_request in req->special.
*/
static int mmc_prep_request(struct request_queue *q, struct request *req)
{
struct mmc_queue *mq = q->queuedata;
int ret = BLKPREP_KILL;
if (req->flags & REQ_SPECIAL) {
/*
* Special commands already have the command
* blocks already setup in req->special.
*/
BUG_ON(!req->special);
ret = BLKPREP_OK;
} else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
/*
* Block I/O requests need translating according
* to the protocol.
*/
ret = mq->prep_fn(mq, req);
} else {
/*
* Everything else is invalid.
*/
blk_dump_rq_flags(req, "MMC bad request");
}
if (ret == BLKPREP_OK)
req->flags |= REQ_DONTPREP;
return ret;
}
static int mmc_queue_thread(void *d)
{
struct mmc_queue *mq = d;
struct request_queue *q = mq->queue;
DECLARE_WAITQUEUE(wait, current);
/*
* Set iothread to ensure that we aren't put to sleep by
* the process freezing. We handle suspension ourselves.
*/
current->flags |= PF_MEMALLOC|PF_NOFREEZE;
daemonize("mmcqd");
complete(&mq->thread_complete);
down(&mq->thread_sem);
add_wait_queue(&mq->thread_wq, &wait);
do {
struct request *req = NULL;
spin_lock_irq(q->queue_lock);
set_current_state(TASK_INTERRUPTIBLE);
if (!blk_queue_plugged(q))
mq->req = req = elv_next_request(q);
spin_unlock_irq(q->queue_lock);
if (!req) {
if (mq->flags & MMC_QUEUE_EXIT)
break;
up(&mq->thread_sem);
schedule();
down(&mq->thread_sem);
continue;
}
set_current_state(TASK_RUNNING);
mq->issue_fn(mq, req);
} while (1);
remove_wait_queue(&mq->thread_wq, &wait);
up(&mq->thread_sem);
complete_and_exit(&mq->thread_complete, 0);
return 0;
}
/*
* Generic MMC request handler. This is called for any queue on a
* particular host. When the host is not busy, we look for a request
* on any queue on this host, and attempt to issue it. This may
* not be the queue we were asked to process.
*/
static void mmc_request(request_queue_t *q)
{
struct mmc_queue *mq = q->queuedata;
if (!mq->req)
wake_up(&mq->thread_wq);
}
/**
* mmc_init_queue - initialise a queue structure.
* @mq: mmc queue
* @card: mmc card to attach this queue
* @lock: queue lock
*
* Initialise a MMC card request queue.
*/
int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock)
{
struct mmc_host *host = card->host;
u64 limit = BLK_BOUNCE_HIGH;
int ret;
if (host->dev->dma_mask && *host->dev->dma_mask)
limit = *host->dev->dma_mask;
mq->card = card;
mq->queue = blk_init_queue(mmc_request, lock);
if (!mq->queue)
return -ENOMEM;
blk_queue_prep_rq(mq->queue, mmc_prep_request);
blk_queue_bounce_limit(mq->queue, limit);
blk_queue_max_sectors(mq->queue, host->max_sectors);
blk_queue_max_phys_segments(mq->queue, host->max_phys_segs);
blk_queue_max_hw_segments(mq->queue, host->max_hw_segs);
blk_queue_max_segment_size(mq->queue, host->max_seg_size);
mq->queue->queuedata = mq;
mq->req = NULL;
mq->sg = kmalloc(sizeof(struct scatterlist) * host->max_phys_segs,
GFP_KERNEL);
if (!mq->sg) {
ret = -ENOMEM;
goto cleanup;
}
init_completion(&mq->thread_complete);
init_waitqueue_head(&mq->thread_wq);
init_MUTEX(&mq->thread_sem);
ret = kernel_thread(mmc_queue_thread, mq, CLONE_KERNEL);
if (ret >= 0) {
wait_for_completion(&mq->thread_complete);
init_completion(&mq->thread_complete);
ret = 0;
goto out;
}
cleanup:
kfree(mq->sg);
mq->sg = NULL;
blk_cleanup_queue(mq->queue);
out:
return ret;
}
EXPORT_SYMBOL(mmc_init_queue);
void mmc_cleanup_queue(struct mmc_queue *mq)
{
mq->flags |= MMC_QUEUE_EXIT;
wake_up(&mq->thread_wq);
wait_for_completion(&mq->thread_complete);
kfree(mq->sg);
mq->sg = NULL;
blk_cleanup_queue(mq->queue);
mq->card = NULL;
}
EXPORT_SYMBOL(mmc_cleanup_queue);
/**
* mmc_queue_suspend - suspend a MMC request queue
* @mq: MMC queue to suspend
*
* Stop the block request queue, and wait for our thread to
* complete any outstanding requests. This ensures that we
* won't suspend while a request is being processed.
*/
void mmc_queue_suspend(struct mmc_queue *mq)
{
request_queue_t *q = mq->queue;
unsigned long flags;
if (!(mq->flags & MMC_QUEUE_SUSPENDED)) {
mq->flags |= MMC_QUEUE_SUSPENDED;
spin_lock_irqsave(q->queue_lock, flags);
blk_stop_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
down(&mq->thread_sem);
}
}
EXPORT_SYMBOL(mmc_queue_suspend);
/**
* mmc_queue_resume - resume a previously suspended MMC request queue
* @mq: MMC queue to resume
*/
void mmc_queue_resume(struct mmc_queue *mq)
{
request_queue_t *q = mq->queue;
unsigned long flags;
if (mq->flags & MMC_QUEUE_SUSPENDED) {
mq->flags &= ~MMC_QUEUE_SUSPENDED;
up(&mq->thread_sem);
spin_lock_irqsave(q->queue_lock, flags);
blk_start_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
}
EXPORT_SYMBOL(mmc_queue_resume);
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...