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>
1 parent df279ca
au1000_xxs1500.c
/*
*
* MyCable board specific pcmcia routines.
*
* Copyright 2003 MontaVista Software Inc.
* Author: Pete Popov, MontaVista Software, Inc.
* ppopov@mvista.com or source@mvista.com
*
* ########################################################################
*
* This program is free software; you can distribute it and/or modify it
* under the terms of the GNU General Public License (Version 2) as
* published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* ########################################################################
*
*
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/tqueue.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/types.h>
#include <pcmcia/cs_types.h>
#include <pcmcia/cs.h>
#include <pcmcia/ss.h>
#include <pcmcia/cistpl.h>
#include <pcmcia/bus_ops.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/au1000.h>
#include <asm/au1000_pcmcia.h>
#define PCMCIA_MAX_SOCK 0
#define PCMCIA_NUM_SOCKS (PCMCIA_MAX_SOCK + 1)
#define PCMCIA_IRQ AU1000_GPIO_4
#if 0
#define DEBUG(x, args...) printk(__func__ ": " x, ##args)
#else
#define DEBUG(x,args...)
#endif
static int xxs1500_pcmcia_init(struct pcmcia_init *init)
{
return PCMCIA_NUM_SOCKS;
}
static int xxs1500_pcmcia_shutdown(void)
{
/* turn off power */
au_writel(au_readl(GPIO2_PINSTATE) | (1<<14)|(1<<30),
GPIO2_OUTPUT);
au_sync_delay(100);
/* assert reset */
au_writel(au_readl(GPIO2_PINSTATE) | (1<<4)|(1<<20),
GPIO2_OUTPUT);
au_sync_delay(100);
return 0;
}
static int
xxs1500_pcmcia_socket_state(unsigned sock, struct pcmcia_state *state)
{
u32 inserted; u32 vs;
unsigned long gpio, gpio2;
if(sock > PCMCIA_MAX_SOCK) return -1;
gpio = au_readl(SYS_PINSTATERD);
gpio2 = au_readl(GPIO2_PINSTATE);
vs = gpio2 & ((1<<8) | (1<<9));
inserted = (!(gpio & 0x1) && !(gpio & 0x2));
state->ready = 0;
state->vs_Xv = 0;
state->vs_3v = 0;
state->detect = 0;
if (inserted) {
switch (vs) {
case 0:
case 1:
case 2:
state->vs_3v=1;
break;
case 3: /* 5V */
default:
/* return without setting 'detect' */
printk(KERN_ERR "au1x00_cs: unsupported VS\n",
vs);
return;
}
state->detect = 1;
}
if (state->detect) {
state->ready = 1;
}
state->bvd1= gpio2 & (1<<10);
state->bvd2 = gpio2 & (1<<11);
state->wrprot=0;
return 1;
}
static int xxs1500_pcmcia_get_irq_info(struct pcmcia_irq_info *info)
{
if(info->sock > PCMCIA_MAX_SOCK) return -1;
info->irq = PCMCIA_IRQ;
return 0;
}
static int
xxs1500_pcmcia_configure_socket(const struct pcmcia_configure *configure)
{
if(configure->sock > PCMCIA_MAX_SOCK) return -1;
DEBUG("Vcc %dV Vpp %dV, reset %d\n",
configure->vcc, configure->vpp, configure->reset);
switch(configure->vcc){
case 33: /* Vcc 3.3V */
/* turn on power */
DEBUG("turn on power\n");
au_writel((au_readl(GPIO2_PINSTATE) & ~(1<<14))|(1<<30),
GPIO2_OUTPUT);
au_sync_delay(100);
break;
case 50: /* Vcc 5V */
default: /* what's this ? */
printk(KERN_ERR "au1x00_cs: unsupported VCC\n");
case 0: /* Vcc 0 */
/* turn off power */
au_sync_delay(100);
au_writel(au_readl(GPIO2_PINSTATE) | (1<<14)|(1<<30),
GPIO2_OUTPUT);
break;
}
if (!configure->reset) {
DEBUG("deassert reset\n");
au_writel((au_readl(GPIO2_PINSTATE) & ~(1<<4))|(1<<20),
GPIO2_OUTPUT);
au_sync_delay(100);
au_writel((au_readl(GPIO2_PINSTATE) & ~(1<<5))|(1<<21),
GPIO2_OUTPUT);
}
else {
DEBUG("assert reset\n");
au_writel(au_readl(GPIO2_PINSTATE) | (1<<4)|(1<<20),
GPIO2_OUTPUT);
}
au_sync_delay(100);
return 0;
}
struct pcmcia_low_level xxs1500_pcmcia_ops = {
xxs1500_pcmcia_init,
xxs1500_pcmcia_shutdown,
xxs1500_pcmcia_socket_state,
xxs1500_pcmcia_get_irq_info,
xxs1500_pcmcia_configure_socket
};
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