Revision d7831a0bdf06b9f722b947bb0c205ff7d77cebd8 authored by Richard Kennedy on 30 June 2009, 18:41:35 UTC, committed by Linus Torvalds on 01 July 2009, 01:56:01 UTC
balance_dirty_pages can overreact and move all of the dirty pages to writeback unnecessarily. balance_dirty_pages makes its decision to throttle based on the number of dirty plus writeback pages that are over the calculated limit,so it will continue to move pages even when there are plenty of pages in writeback and less than the threshold still dirty. This allows it to overshoot its limits and move all the dirty pages to writeback while waiting for the drives to catch up and empty the writeback list. A simple fio test easily demonstrates this problem. fio --name=f1 --directory=/disk1 --size=2G -rw=write --name=f2 --directory=/disk2 --size=1G --rw=write --startdelay=10 This is the simplest fix I could find, but I'm not entirely sure that it alone will be enough for all cases. But it certainly is an improvement on my desktop machine writing to 2 disks. Do we need something more for machines with large arrays where bdi_threshold * number_of_drives is greater than the dirty_ratio ? Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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sa1100_assabet.c
/*
* drivers/pcmcia/sa1100_assabet.c
*
* PCMCIA implementation routines for Assabet
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/init.h>
#include <mach/hardware.h>
#include <asm/mach-types.h>
#include <asm/irq.h>
#include <asm/signal.h>
#include <mach/assabet.h>
#include "sa1100_generic.h"
static struct pcmcia_irqs irqs[] = {
{ 1, ASSABET_IRQ_GPIO_CF_CD, "CF CD" },
{ 1, ASSABET_IRQ_GPIO_CF_BVD2, "CF BVD2" },
{ 1, ASSABET_IRQ_GPIO_CF_BVD1, "CF BVD1" },
};
static int assabet_pcmcia_hw_init(struct soc_pcmcia_socket *skt)
{
skt->irq = ASSABET_IRQ_GPIO_CF_IRQ;
return soc_pcmcia_request_irqs(skt, irqs, ARRAY_SIZE(irqs));
}
/*
* Release all resources.
*/
static void assabet_pcmcia_hw_shutdown(struct soc_pcmcia_socket *skt)
{
soc_pcmcia_free_irqs(skt, irqs, ARRAY_SIZE(irqs));
}
static void
assabet_pcmcia_socket_state(struct soc_pcmcia_socket *skt, struct pcmcia_state *state)
{
unsigned long levels = GPLR;
state->detect = (levels & ASSABET_GPIO_CF_CD) ? 0 : 1;
state->ready = (levels & ASSABET_GPIO_CF_IRQ) ? 1 : 0;
state->bvd1 = (levels & ASSABET_GPIO_CF_BVD1) ? 1 : 0;
state->bvd2 = (levels & ASSABET_GPIO_CF_BVD2) ? 1 : 0;
state->wrprot = 0; /* Not available on Assabet. */
state->vs_3v = 1; /* Can only apply 3.3V on Assabet. */
state->vs_Xv = 0;
}
static int
assabet_pcmcia_configure_socket(struct soc_pcmcia_socket *skt, const socket_state_t *state)
{
unsigned int mask;
switch (state->Vcc) {
case 0:
mask = 0;
break;
case 50:
printk(KERN_WARNING "%s(): CS asked for 5V, applying 3.3V...\n",
__func__);
case 33: /* Can only apply 3.3V to the CF slot. */
mask = ASSABET_BCR_CF_PWR;
break;
default:
printk(KERN_ERR "%s(): unrecognized Vcc %u\n", __func__,
state->Vcc);
return -1;
}
/* Silently ignore Vpp, output enable, speaker enable. */
if (state->flags & SS_RESET)
mask |= ASSABET_BCR_CF_RST;
ASSABET_BCR_frob(ASSABET_BCR_CF_RST | ASSABET_BCR_CF_PWR, mask);
return 0;
}
/*
* Enable card status IRQs on (re-)initialisation. This can
* be called at initialisation, power management event, or
* pcmcia event.
*/
static void assabet_pcmcia_socket_init(struct soc_pcmcia_socket *skt)
{
/*
* Enable CF bus
*/
ASSABET_BCR_clear(ASSABET_BCR_CF_BUS_OFF);
soc_pcmcia_enable_irqs(skt, irqs, ARRAY_SIZE(irqs));
}
/*
* Disable card status IRQs on suspend.
*/
static void assabet_pcmcia_socket_suspend(struct soc_pcmcia_socket *skt)
{
soc_pcmcia_disable_irqs(skt, irqs, ARRAY_SIZE(irqs));
/*
* Tristate the CF bus signals. Also assert CF
* reset as per user guide page 4-11.
*/
ASSABET_BCR_set(ASSABET_BCR_CF_BUS_OFF | ASSABET_BCR_CF_RST);
}
static struct pcmcia_low_level assabet_pcmcia_ops = {
.owner = THIS_MODULE,
.hw_init = assabet_pcmcia_hw_init,
.hw_shutdown = assabet_pcmcia_hw_shutdown,
.socket_state = assabet_pcmcia_socket_state,
.configure_socket = assabet_pcmcia_configure_socket,
.socket_init = assabet_pcmcia_socket_init,
.socket_suspend = assabet_pcmcia_socket_suspend,
};
int __init pcmcia_assabet_init(struct device *dev)
{
int ret = -ENODEV;
if (machine_is_assabet() && !machine_has_neponset())
ret = sa11xx_drv_pcmcia_probe(dev, &assabet_pcmcia_ops, 1, 1);
return ret;
}
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