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
electra_cf.c
/*
* Copyright (C) 2007 PA Semi, Inc
*
* Maintained by: Olof Johansson <olof@lixom.net>
*
* Based on drivers/pcmcia/omap_cf.c
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that 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/kernel.h>
#include <linux/sched.h>
#include <linux/platform_device.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/of_platform.h>
#include <pcmcia/ss.h>
static const char driver_name[] = "electra-cf";
struct electra_cf_socket {
struct pcmcia_socket socket;
struct timer_list timer;
unsigned present:1;
unsigned active:1;
struct of_device *ofdev;
unsigned long mem_phys;
void __iomem * mem_base;
unsigned long mem_size;
void __iomem * io_virt;
unsigned int io_base;
unsigned int io_size;
u_int irq;
struct resource iomem;
void __iomem * gpio_base;
int gpio_detect;
int gpio_vsense;
int gpio_3v;
int gpio_5v;
};
#define POLL_INTERVAL (2 * HZ)
static int electra_cf_present(struct electra_cf_socket *cf)
{
unsigned int gpio;
gpio = in_le32(cf->gpio_base+0x40);
return !(gpio & (1 << cf->gpio_detect));
}
static int electra_cf_ss_init(struct pcmcia_socket *s)
{
return 0;
}
/* the timer is primarily to kick this socket's pccardd */
static void electra_cf_timer(unsigned long _cf)
{
struct electra_cf_socket *cf = (void *) _cf;
int present = electra_cf_present(cf);
if (present != cf->present) {
cf->present = present;
pcmcia_parse_events(&cf->socket, SS_DETECT);
}
if (cf->active)
mod_timer(&cf->timer, jiffies + POLL_INTERVAL);
}
static irqreturn_t electra_cf_irq(int irq, void *_cf)
{
electra_cf_timer((unsigned long)_cf);
return IRQ_HANDLED;
}
static int electra_cf_get_status(struct pcmcia_socket *s, u_int *sp)
{
struct electra_cf_socket *cf;
if (!sp)
return -EINVAL;
cf = container_of(s, struct electra_cf_socket, socket);
/* NOTE CF is always 3VCARD */
if (electra_cf_present(cf)) {
*sp = SS_READY | SS_DETECT | SS_POWERON | SS_3VCARD;
s->pci_irq = cf->irq;
} else
*sp = 0;
return 0;
}
static int electra_cf_set_socket(struct pcmcia_socket *sock,
struct socket_state_t *s)
{
unsigned int gpio;
unsigned int vcc;
struct electra_cf_socket *cf;
cf = container_of(sock, struct electra_cf_socket, socket);
/* "reset" means no power in our case */
vcc = (s->flags & SS_RESET) ? 0 : s->Vcc;
switch (vcc) {
case 0:
gpio = 0;
break;
case 33:
gpio = (1 << cf->gpio_3v);
break;
case 5:
gpio = (1 << cf->gpio_5v);
break;
default:
return -EINVAL;
}
gpio |= 1 << (cf->gpio_3v + 16); /* enwr */
gpio |= 1 << (cf->gpio_5v + 16); /* enwr */
out_le32(cf->gpio_base+0x90, gpio);
pr_debug("%s: Vcc %d, io_irq %d, flags %04x csc %04x\n",
driver_name, s->Vcc, s->io_irq, s->flags, s->csc_mask);
return 0;
}
static int electra_cf_set_io_map(struct pcmcia_socket *s,
struct pccard_io_map *io)
{
return 0;
}
static int electra_cf_set_mem_map(struct pcmcia_socket *s,
struct pccard_mem_map *map)
{
struct electra_cf_socket *cf;
if (map->card_start)
return -EINVAL;
cf = container_of(s, struct electra_cf_socket, socket);
map->static_start = cf->mem_phys;
map->flags &= MAP_ACTIVE|MAP_ATTRIB;
if (!(map->flags & MAP_ATTRIB))
map->static_start += 0x800;
return 0;
}
static struct pccard_operations electra_cf_ops = {
.init = electra_cf_ss_init,
.get_status = electra_cf_get_status,
.set_socket = electra_cf_set_socket,
.set_io_map = electra_cf_set_io_map,
.set_mem_map = electra_cf_set_mem_map,
};
static int __devinit electra_cf_probe(struct of_device *ofdev,
const struct of_device_id *match)
{
struct device *device = &ofdev->dev;
struct device_node *np = ofdev->node;
struct electra_cf_socket *cf;
struct resource mem, io;
int status;
const unsigned int *prop;
int err;
struct vm_struct *area;
err = of_address_to_resource(np, 0, &mem);
if (err)
return -EINVAL;
err = of_address_to_resource(np, 1, &io);
if (err)
return -EINVAL;
cf = kzalloc(sizeof *cf, GFP_KERNEL);
if (!cf)
return -ENOMEM;
setup_timer(&cf->timer, electra_cf_timer, (unsigned long)cf);
cf->irq = NO_IRQ;
cf->ofdev = ofdev;
cf->mem_phys = mem.start;
cf->mem_size = PAGE_ALIGN(mem.end - mem.start);
cf->mem_base = ioremap(cf->mem_phys, cf->mem_size);
cf->io_size = PAGE_ALIGN(io.end - io.start);
area = __get_vm_area(cf->io_size, 0, PHB_IO_BASE, PHB_IO_END);
if (area == NULL)
return -ENOMEM;
cf->io_virt = (void __iomem *)(area->addr);
cf->gpio_base = ioremap(0xfc103000, 0x1000);
dev_set_drvdata(device, cf);
if (!cf->mem_base || !cf->io_virt || !cf->gpio_base ||
(__ioremap_at(io.start, cf->io_virt, cf->io_size,
_PAGE_NO_CACHE | _PAGE_GUARDED) == NULL)) {
dev_err(device, "can't ioremap ranges\n");
status = -ENOMEM;
goto fail1;
}
cf->io_base = (unsigned long)cf->io_virt - VMALLOC_END;
cf->iomem.start = (unsigned long)cf->mem_base;
cf->iomem.end = (unsigned long)cf->mem_base + (mem.end - mem.start);
cf->iomem.flags = IORESOURCE_MEM;
cf->irq = irq_of_parse_and_map(np, 0);
status = request_irq(cf->irq, electra_cf_irq, IRQF_SHARED,
driver_name, cf);
if (status < 0) {
dev_err(device, "request_irq failed\n");
goto fail1;
}
cf->socket.pci_irq = cf->irq;
prop = of_get_property(np, "card-detect-gpio", NULL);
if (!prop)
goto fail1;
cf->gpio_detect = *prop;
prop = of_get_property(np, "card-vsense-gpio", NULL);
if (!prop)
goto fail1;
cf->gpio_vsense = *prop;
prop = of_get_property(np, "card-3v-gpio", NULL);
if (!prop)
goto fail1;
cf->gpio_3v = *prop;
prop = of_get_property(np, "card-5v-gpio", NULL);
if (!prop)
goto fail1;
cf->gpio_5v = *prop;
cf->socket.io_offset = cf->io_base;
/* reserve chip-select regions */
if (!request_mem_region(cf->mem_phys, cf->mem_size, driver_name)) {
status = -ENXIO;
dev_err(device, "Can't claim memory region\n");
goto fail1;
}
if (!request_region(cf->io_base, cf->io_size, driver_name)) {
status = -ENXIO;
dev_err(device, "Can't claim I/O region\n");
goto fail2;
}
cf->socket.owner = THIS_MODULE;
cf->socket.dev.parent = &ofdev->dev;
cf->socket.ops = &electra_cf_ops;
cf->socket.resource_ops = &pccard_static_ops;
cf->socket.features = SS_CAP_PCCARD | SS_CAP_STATIC_MAP |
SS_CAP_MEM_ALIGN;
cf->socket.map_size = 0x800;
status = pcmcia_register_socket(&cf->socket);
if (status < 0) {
dev_err(device, "pcmcia_register_socket failed\n");
goto fail3;
}
dev_info(device, "at mem 0x%lx io 0x%llx irq %d\n",
cf->mem_phys, io.start, cf->irq);
cf->active = 1;
electra_cf_timer((unsigned long)cf);
return 0;
fail3:
release_region(cf->io_base, cf->io_size);
fail2:
release_mem_region(cf->mem_phys, cf->mem_size);
fail1:
if (cf->irq != NO_IRQ)
free_irq(cf->irq, cf);
if (cf->io_virt)
__iounmap_at(cf->io_virt, cf->io_size);
if (cf->mem_base)
iounmap(cf->mem_base);
if (cf->gpio_base)
iounmap(cf->gpio_base);
device_init_wakeup(&ofdev->dev, 0);
kfree(cf);
return status;
}
static int __devexit electra_cf_remove(struct of_device *ofdev)
{
struct device *device = &ofdev->dev;
struct electra_cf_socket *cf;
cf = dev_get_drvdata(device);
cf->active = 0;
pcmcia_unregister_socket(&cf->socket);
free_irq(cf->irq, cf);
del_timer_sync(&cf->timer);
__iounmap_at(cf->io_virt, cf->io_size);
iounmap(cf->mem_base);
iounmap(cf->gpio_base);
release_mem_region(cf->mem_phys, cf->mem_size);
release_region(cf->io_base, cf->io_size);
kfree(cf);
return 0;
}
static struct of_device_id electra_cf_match[] = {
{
.compatible = "electra-cf",
},
{},
};
MODULE_DEVICE_TABLE(of, electra_cf_match);
static struct of_platform_driver electra_cf_driver = {
.name = (char *)driver_name,
.match_table = electra_cf_match,
.probe = electra_cf_probe,
.remove = electra_cf_remove,
};
static int __init electra_cf_init(void)
{
return of_register_platform_driver(&electra_cf_driver);
}
module_init(electra_cf_init);
static void __exit electra_cf_exit(void)
{
of_unregister_platform_driver(&electra_cf_driver);
}
module_exit(electra_cf_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR ("Olof Johansson <olof@lixom.net>");
MODULE_DESCRIPTION("PA Semi Electra CF driver");
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