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
at91_cf.c
/*
* at91_cf.c -- AT91 CompactFlash controller driver
*
* Copyright (C) 2005 David Brownell
*
* 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.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <pcmcia/ss.h>
#include <mach/hardware.h>
#include <asm/io.h>
#include <asm/sizes.h>
#include <asm/gpio.h>
#include <mach/board.h>
#include <mach/at91rm9200_mc.h>
/*
* A0..A10 work in each range; A23 indicates I/O space; A25 is CFRNW;
* some other bit in {A24,A22..A11} is nREG to flag memory access
* (vs attributes). So more than 2KB/region would just be waste.
* Note: These are offsets from the physical base address.
*/
#define CF_ATTR_PHYS (0)
#define CF_IO_PHYS (1 << 23)
#define CF_MEM_PHYS (0x017ff800)
/*--------------------------------------------------------------------------*/
static const char driver_name[] = "at91_cf";
struct at91_cf_socket {
struct pcmcia_socket socket;
unsigned present:1;
struct platform_device *pdev;
struct at91_cf_data *board;
unsigned long phys_baseaddr;
};
#define SZ_2K (2 * SZ_1K)
static inline int at91_cf_present(struct at91_cf_socket *cf)
{
return !gpio_get_value(cf->board->det_pin);
}
/*--------------------------------------------------------------------------*/
static int at91_cf_ss_init(struct pcmcia_socket *s)
{
return 0;
}
static irqreturn_t at91_cf_irq(int irq, void *_cf)
{
struct at91_cf_socket *cf = _cf;
if (irq == cf->board->det_pin) {
unsigned present = at91_cf_present(cf);
/* kick pccard as needed */
if (present != cf->present) {
cf->present = present;
pr_debug("%s: card %s\n", driver_name,
present ? "present" : "gone");
pcmcia_parse_events(&cf->socket, SS_DETECT);
}
}
return IRQ_HANDLED;
}
static int at91_cf_get_status(struct pcmcia_socket *s, u_int *sp)
{
struct at91_cf_socket *cf;
if (!sp)
return -EINVAL;
cf = container_of(s, struct at91_cf_socket, socket);
/* NOTE: CF is always 3VCARD */
if (at91_cf_present(cf)) {
int rdy = cf->board->irq_pin; /* RDY/nIRQ */
int vcc = cf->board->vcc_pin;
*sp = SS_DETECT | SS_3VCARD;
if (!rdy || gpio_get_value(rdy))
*sp |= SS_READY;
if (!vcc || gpio_get_value(vcc))
*sp |= SS_POWERON;
} else
*sp = 0;
return 0;
}
static int
at91_cf_set_socket(struct pcmcia_socket *sock, struct socket_state_t *s)
{
struct at91_cf_socket *cf;
cf = container_of(sock, struct at91_cf_socket, socket);
/* switch Vcc if needed and possible */
if (cf->board->vcc_pin) {
switch (s->Vcc) {
case 0:
gpio_set_value(cf->board->vcc_pin, 0);
break;
case 33:
gpio_set_value(cf->board->vcc_pin, 1);
break;
default:
return -EINVAL;
}
}
/* toggle reset if needed */
gpio_set_value(cf->board->rst_pin, s->flags & SS_RESET);
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 at91_cf_ss_suspend(struct pcmcia_socket *s)
{
return at91_cf_set_socket(s, &dead_socket);
}
/* we already mapped the I/O region */
static int at91_cf_set_io_map(struct pcmcia_socket *s, struct pccard_io_map *io)
{
struct at91_cf_socket *cf;
u32 csr;
cf = container_of(s, struct at91_cf_socket, socket);
io->flags &= (MAP_ACTIVE | MAP_16BIT | MAP_AUTOSZ);
/*
* Use 16 bit accesses unless/until we need 8-bit i/o space.
*/
csr = at91_sys_read(AT91_SMC_CSR(cf->board->chipselect)) & ~AT91_SMC_DBW;
/*
* NOTE: this CF controller ignores IOIS16, so we can't really do
* MAP_AUTOSZ. The 16bit mode allows single byte access on either
* D0-D7 (even addr) or D8-D15 (odd), so it's close enough for many
* purposes (and handles ide-cs).
*
* The 8bit mode is needed for odd byte access on D0-D7. It seems
* some cards only like that way to get at the odd byte, despite
* CF 3.0 spec table 35 also giving the D8-D15 option.
*/
if (!(io->flags & (MAP_16BIT | MAP_AUTOSZ))) {
csr |= AT91_SMC_DBW_8;
pr_debug("%s: 8bit i/o bus\n", driver_name);
} else {
csr |= AT91_SMC_DBW_16;
pr_debug("%s: 16bit i/o bus\n", driver_name);
}
at91_sys_write(AT91_SMC_CSR(cf->board->chipselect), csr);
io->start = cf->socket.io_offset;
io->stop = io->start + SZ_2K - 1;
return 0;
}
/* pcmcia layer maps/unmaps mem regions */
static int
at91_cf_set_mem_map(struct pcmcia_socket *s, struct pccard_mem_map *map)
{
struct at91_cf_socket *cf;
if (map->card_start)
return -EINVAL;
cf = container_of(s, struct at91_cf_socket, socket);
map->flags &= (MAP_ACTIVE | MAP_ATTRIB | MAP_16BIT);
if (map->flags & MAP_ATTRIB)
map->static_start = cf->phys_baseaddr + CF_ATTR_PHYS;
else
map->static_start = cf->phys_baseaddr + CF_MEM_PHYS;
return 0;
}
static struct pccard_operations at91_cf_ops = {
.init = at91_cf_ss_init,
.suspend = at91_cf_ss_suspend,
.get_status = at91_cf_get_status,
.set_socket = at91_cf_set_socket,
.set_io_map = at91_cf_set_io_map,
.set_mem_map = at91_cf_set_mem_map,
};
/*--------------------------------------------------------------------------*/
static int __init at91_cf_probe(struct platform_device *pdev)
{
struct at91_cf_socket *cf;
struct at91_cf_data *board = pdev->dev.platform_data;
struct resource *io;
int status;
if (!board || !board->det_pin || !board->rst_pin)
return -ENODEV;
io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!io)
return -ENODEV;
cf = kzalloc(sizeof *cf, GFP_KERNEL);
if (!cf)
return -ENOMEM;
cf->board = board;
cf->pdev = pdev;
cf->phys_baseaddr = io->start;
platform_set_drvdata(pdev, cf);
/* must be a GPIO; ergo must trigger on both edges */
status = gpio_request(board->det_pin, "cf_det");
if (status < 0)
goto fail0;
status = request_irq(board->det_pin, at91_cf_irq, 0, driver_name, cf);
if (status < 0)
goto fail00;
device_init_wakeup(&pdev->dev, 1);
status = gpio_request(board->rst_pin, "cf_rst");
if (status < 0)
goto fail0a;
if (board->vcc_pin) {
status = gpio_request(board->vcc_pin, "cf_vcc");
if (status < 0)
goto fail0b;
}
/*
* The card driver will request this irq later as needed.
* but it causes lots of "irqNN: nobody cared" messages
* unless we report that we handle everything (sigh).
* (Note: DK board doesn't wire the IRQ pin...)
*/
if (board->irq_pin) {
status = gpio_request(board->irq_pin, "cf_irq");
if (status < 0)
goto fail0c;
status = request_irq(board->irq_pin, at91_cf_irq,
IRQF_SHARED, driver_name, cf);
if (status < 0)
goto fail0d;
cf->socket.pci_irq = board->irq_pin;
} else
cf->socket.pci_irq = nr_irqs + 1;
/* pcmcia layer only remaps "real" memory not iospace */
cf->socket.io_offset = (unsigned long)
ioremap(cf->phys_baseaddr + CF_IO_PHYS, SZ_2K);
if (!cf->socket.io_offset) {
status = -ENXIO;
goto fail1;
}
/* reserve chip-select regions */
if (!request_mem_region(io->start, io->end + 1 - io->start,
driver_name)) {
status = -ENXIO;
goto fail1;
}
pr_info("%s: irqs det #%d, io #%d\n", driver_name,
board->det_pin, board->irq_pin);
cf->socket.owner = THIS_MODULE;
cf->socket.dev.parent = &pdev->dev;
cf->socket.ops = &at91_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 = SZ_2K;
cf->socket.io[0].res = io;
status = pcmcia_register_socket(&cf->socket);
if (status < 0)
goto fail2;
return 0;
fail2:
release_mem_region(io->start, io->end + 1 - io->start);
fail1:
if (cf->socket.io_offset)
iounmap((void __iomem *) cf->socket.io_offset);
if (board->irq_pin) {
free_irq(board->irq_pin, cf);
fail0d:
gpio_free(board->irq_pin);
}
fail0c:
if (board->vcc_pin)
gpio_free(board->vcc_pin);
fail0b:
gpio_free(board->rst_pin);
fail0a:
device_init_wakeup(&pdev->dev, 0);
free_irq(board->det_pin, cf);
fail00:
gpio_free(board->det_pin);
fail0:
kfree(cf);
return status;
}
static int __exit at91_cf_remove(struct platform_device *pdev)
{
struct at91_cf_socket *cf = platform_get_drvdata(pdev);
struct at91_cf_data *board = cf->board;
struct resource *io = cf->socket.io[0].res;
pcmcia_unregister_socket(&cf->socket);
release_mem_region(io->start, io->end + 1 - io->start);
iounmap((void __iomem *) cf->socket.io_offset);
if (board->irq_pin) {
free_irq(board->irq_pin, cf);
gpio_free(board->irq_pin);
}
if (board->vcc_pin)
gpio_free(board->vcc_pin);
gpio_free(board->rst_pin);
device_init_wakeup(&pdev->dev, 0);
free_irq(board->det_pin, cf);
gpio_free(board->det_pin);
kfree(cf);
return 0;
}
#ifdef CONFIG_PM
static int at91_cf_suspend(struct platform_device *pdev, pm_message_t mesg)
{
struct at91_cf_socket *cf = platform_get_drvdata(pdev);
struct at91_cf_data *board = cf->board;
pcmcia_socket_dev_suspend(&pdev->dev, mesg);
if (device_may_wakeup(&pdev->dev)) {
enable_irq_wake(board->det_pin);
if (board->irq_pin)
enable_irq_wake(board->irq_pin);
}
return 0;
}
static int at91_cf_resume(struct platform_device *pdev)
{
struct at91_cf_socket *cf = platform_get_drvdata(pdev);
struct at91_cf_data *board = cf->board;
if (device_may_wakeup(&pdev->dev)) {
disable_irq_wake(board->det_pin);
if (board->irq_pin)
disable_irq_wake(board->irq_pin);
}
pcmcia_socket_dev_resume(&pdev->dev);
return 0;
}
#else
#define at91_cf_suspend NULL
#define at91_cf_resume NULL
#endif
static struct platform_driver at91_cf_driver = {
.driver = {
.name = (char *) driver_name,
.owner = THIS_MODULE,
},
.remove = __exit_p(at91_cf_remove),
.suspend = at91_cf_suspend,
.resume = at91_cf_resume,
};
/*--------------------------------------------------------------------------*/
static int __init at91_cf_init(void)
{
return platform_driver_probe(&at91_cf_driver, at91_cf_probe);
}
module_init(at91_cf_init);
static void __exit at91_cf_exit(void)
{
platform_driver_unregister(&at91_cf_driver);
}
module_exit(at91_cf_exit);
MODULE_DESCRIPTION("AT91 Compact Flash Driver");
MODULE_AUTHOR("David Brownell");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:at91_cf");
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