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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pxa2xx_base.c
/*======================================================================
Device driver for the PCMCIA control functionality of PXA2xx
microprocessors.
The contents of this file may be used under the
terms of the GNU Public License version 2 (the "GPL")
(c) Ian Molton (spyro@f2s.com) 2003
(c) Stefan Eletzhofer (stefan.eletzhofer@inquant.de) 2003,4
derived from sa11xx_base.c
Portions created by John G. Dorsey are
Copyright (C) 1999 John G. Dorsey.
======================================================================*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <mach/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <mach/pxa2xx-regs.h>
#include <asm/mach-types.h>
#include <pcmcia/cs_types.h>
#include <pcmcia/ss.h>
#include <pcmcia/cistpl.h>
#include "soc_common.h"
#include "pxa2xx_base.h"
/*
* Personal Computer Memory Card International Association (PCMCIA) sockets
*/
#define PCMCIAPrtSp 0x04000000 /* PCMCIA Partition Space [byte] */
#define PCMCIASp (4*PCMCIAPrtSp) /* PCMCIA Space [byte] */
#define PCMCIAIOSp PCMCIAPrtSp /* PCMCIA I/O Space [byte] */
#define PCMCIAAttrSp PCMCIAPrtSp /* PCMCIA Attribute Space [byte] */
#define PCMCIAMemSp PCMCIAPrtSp /* PCMCIA Memory Space [byte] */
#define PCMCIA0Sp PCMCIASp /* PCMCIA 0 Space [byte] */
#define PCMCIA0IOSp PCMCIAIOSp /* PCMCIA 0 I/O Space [byte] */
#define PCMCIA0AttrSp PCMCIAAttrSp /* PCMCIA 0 Attribute Space [byte] */
#define PCMCIA0MemSp PCMCIAMemSp /* PCMCIA 0 Memory Space [byte] */
#define PCMCIA1Sp PCMCIASp /* PCMCIA 1 Space [byte] */
#define PCMCIA1IOSp PCMCIAIOSp /* PCMCIA 1 I/O Space [byte] */
#define PCMCIA1AttrSp PCMCIAAttrSp /* PCMCIA 1 Attribute Space [byte] */
#define PCMCIA1MemSp PCMCIAMemSp /* PCMCIA 1 Memory Space [byte] */
#define _PCMCIA(Nb) /* PCMCIA [0..1] */ \
(0x20000000 + (Nb) * PCMCIASp)
#define _PCMCIAIO(Nb) _PCMCIA(Nb) /* PCMCIA I/O [0..1] */
#define _PCMCIAAttr(Nb) /* PCMCIA Attribute [0..1] */ \
(_PCMCIA(Nb) + 2 * PCMCIAPrtSp)
#define _PCMCIAMem(Nb) /* PCMCIA Memory [0..1] */ \
(_PCMCIA(Nb) + 3 * PCMCIAPrtSp)
#define _PCMCIA0 _PCMCIA(0) /* PCMCIA 0 */
#define _PCMCIA0IO _PCMCIAIO(0) /* PCMCIA 0 I/O */
#define _PCMCIA0Attr _PCMCIAAttr(0) /* PCMCIA 0 Attribute */
#define _PCMCIA0Mem _PCMCIAMem(0) /* PCMCIA 0 Memory */
#define _PCMCIA1 _PCMCIA(1) /* PCMCIA 1 */
#define _PCMCIA1IO _PCMCIAIO(1) /* PCMCIA 1 I/O */
#define _PCMCIA1Attr _PCMCIAAttr(1) /* PCMCIA 1 Attribute */
#define _PCMCIA1Mem _PCMCIAMem(1) /* PCMCIA 1 Memory */
#define MCXX_SETUP_MASK (0x7f)
#define MCXX_ASST_MASK (0x1f)
#define MCXX_HOLD_MASK (0x3f)
#define MCXX_SETUP_SHIFT (0)
#define MCXX_ASST_SHIFT (7)
#define MCXX_HOLD_SHIFT (14)
static inline u_int pxa2xx_mcxx_hold(u_int pcmcia_cycle_ns,
u_int mem_clk_10khz)
{
u_int code = pcmcia_cycle_ns * mem_clk_10khz;
return (code / 300000) + ((code % 300000) ? 1 : 0) - 1;
}
static inline u_int pxa2xx_mcxx_asst(u_int pcmcia_cycle_ns,
u_int mem_clk_10khz)
{
u_int code = pcmcia_cycle_ns * mem_clk_10khz;
return (code / 300000) + ((code % 300000) ? 1 : 0) + 1;
}
static inline u_int pxa2xx_mcxx_setup(u_int pcmcia_cycle_ns,
u_int mem_clk_10khz)
{
u_int code = pcmcia_cycle_ns * mem_clk_10khz;
return (code / 100000) + ((code % 100000) ? 1 : 0) - 1;
}
/* This function returns the (approximate) command assertion period, in
* nanoseconds, for a given CPU clock frequency and MCXX_ASST value:
*/
static inline u_int pxa2xx_pcmcia_cmd_time(u_int mem_clk_10khz,
u_int pcmcia_mcxx_asst)
{
return (300000 * (pcmcia_mcxx_asst + 1) / mem_clk_10khz);
}
static int pxa2xx_pcmcia_set_mcmem( int sock, int speed, int clock )
{
MCMEM(sock) = ((pxa2xx_mcxx_setup(speed, clock)
& MCXX_SETUP_MASK) << MCXX_SETUP_SHIFT)
| ((pxa2xx_mcxx_asst(speed, clock)
& MCXX_ASST_MASK) << MCXX_ASST_SHIFT)
| ((pxa2xx_mcxx_hold(speed, clock)
& MCXX_HOLD_MASK) << MCXX_HOLD_SHIFT);
return 0;
}
static int pxa2xx_pcmcia_set_mcio( int sock, int speed, int clock )
{
MCIO(sock) = ((pxa2xx_mcxx_setup(speed, clock)
& MCXX_SETUP_MASK) << MCXX_SETUP_SHIFT)
| ((pxa2xx_mcxx_asst(speed, clock)
& MCXX_ASST_MASK) << MCXX_ASST_SHIFT)
| ((pxa2xx_mcxx_hold(speed, clock)
& MCXX_HOLD_MASK) << MCXX_HOLD_SHIFT);
return 0;
}
static int pxa2xx_pcmcia_set_mcatt( int sock, int speed, int clock )
{
MCATT(sock) = ((pxa2xx_mcxx_setup(speed, clock)
& MCXX_SETUP_MASK) << MCXX_SETUP_SHIFT)
| ((pxa2xx_mcxx_asst(speed, clock)
& MCXX_ASST_MASK) << MCXX_ASST_SHIFT)
| ((pxa2xx_mcxx_hold(speed, clock)
& MCXX_HOLD_MASK) << MCXX_HOLD_SHIFT);
return 0;
}
static int pxa2xx_pcmcia_set_mcxx(struct soc_pcmcia_socket *skt, unsigned int clk)
{
struct soc_pcmcia_timing timing;
int sock = skt->nr;
soc_common_pcmcia_get_timing(skt, &timing);
pxa2xx_pcmcia_set_mcmem(sock, timing.mem, clk);
pxa2xx_pcmcia_set_mcatt(sock, timing.attr, clk);
pxa2xx_pcmcia_set_mcio(sock, timing.io, clk);
return 0;
}
static int pxa2xx_pcmcia_set_timing(struct soc_pcmcia_socket *skt)
{
unsigned int clk = get_memclk_frequency_10khz();
return pxa2xx_pcmcia_set_mcxx(skt, clk);
}
#ifdef CONFIG_CPU_FREQ
static int
pxa2xx_pcmcia_frequency_change(struct soc_pcmcia_socket *skt,
unsigned long val,
struct cpufreq_freqs *freqs)
{
#warning "it's not clear if this is right since the core CPU (N) clock has no effect on the memory (L) clock"
switch (val) {
case CPUFREQ_PRECHANGE:
if (freqs->new > freqs->old) {
debug(skt, 2, "new frequency %u.%uMHz > %u.%uMHz, "
"pre-updating\n",
freqs->new / 1000, (freqs->new / 100) % 10,
freqs->old / 1000, (freqs->old / 100) % 10);
pxa2xx_pcmcia_set_mcxx(skt, freqs->new);
}
break;
case CPUFREQ_POSTCHANGE:
if (freqs->new < freqs->old) {
debug(skt, 2, "new frequency %u.%uMHz < %u.%uMHz, "
"post-updating\n",
freqs->new / 1000, (freqs->new / 100) % 10,
freqs->old / 1000, (freqs->old / 100) % 10);
pxa2xx_pcmcia_set_mcxx(skt, freqs->new);
}
break;
}
return 0;
}
#endif
static void pxa2xx_configure_sockets(struct device *dev)
{
struct pcmcia_low_level *ops = dev->platform_data;
/*
* We have at least one socket, so set MECR:CIT
* (Card Is There)
*/
MECR |= MECR_CIT;
/* Set MECR:NOS (Number Of Sockets) */
if ((ops->first + ops->nr) > 1 || machine_is_viper())
MECR |= MECR_NOS;
else
MECR &= ~MECR_NOS;
}
static const char *skt_names[] = {
"PCMCIA socket 0",
"PCMCIA socket 1",
};
#define SKT_DEV_INFO_SIZE(n) \
(sizeof(struct skt_dev_info) + (n)*sizeof(struct soc_pcmcia_socket))
int __pxa2xx_drv_pcmcia_probe(struct device *dev)
{
int i, ret;
struct pcmcia_low_level *ops;
struct skt_dev_info *sinfo;
struct soc_pcmcia_socket *skt;
if (!dev || !dev->platform_data)
return -ENODEV;
ops = (struct pcmcia_low_level *)dev->platform_data;
sinfo = kzalloc(SKT_DEV_INFO_SIZE(ops->nr), GFP_KERNEL);
if (!sinfo)
return -ENOMEM;
sinfo->nskt = ops->nr;
/* Initialize processor specific parameters */
for (i = 0; i < ops->nr; i++) {
skt = &sinfo->skt[i];
skt->nr = ops->first + i;
skt->irq = NO_IRQ;
skt->res_skt.start = _PCMCIA(skt->nr);
skt->res_skt.end = _PCMCIA(skt->nr) + PCMCIASp - 1;
skt->res_skt.name = skt_names[skt->nr];
skt->res_skt.flags = IORESOURCE_MEM;
skt->res_io.start = _PCMCIAIO(skt->nr);
skt->res_io.end = _PCMCIAIO(skt->nr) + PCMCIAIOSp - 1;
skt->res_io.name = "io";
skt->res_io.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
skt->res_mem.start = _PCMCIAMem(skt->nr);
skt->res_mem.end = _PCMCIAMem(skt->nr) + PCMCIAMemSp - 1;
skt->res_mem.name = "memory";
skt->res_mem.flags = IORESOURCE_MEM;
skt->res_attr.start = _PCMCIAAttr(skt->nr);
skt->res_attr.end = _PCMCIAAttr(skt->nr) + PCMCIAAttrSp - 1;
skt->res_attr.name = "attribute";
skt->res_attr.flags = IORESOURCE_MEM;
}
/* Provide our PXA2xx specific timing routines. */
ops->set_timing = pxa2xx_pcmcia_set_timing;
#ifdef CONFIG_CPU_FREQ
ops->frequency_change = pxa2xx_pcmcia_frequency_change;
#endif
ret = soc_common_drv_pcmcia_probe(dev, ops, sinfo);
if (!ret)
pxa2xx_configure_sockets(dev);
return ret;
}
EXPORT_SYMBOL(__pxa2xx_drv_pcmcia_probe);
static int pxa2xx_drv_pcmcia_probe(struct platform_device *dev)
{
return __pxa2xx_drv_pcmcia_probe(&dev->dev);
}
static int pxa2xx_drv_pcmcia_remove(struct platform_device *dev)
{
return soc_common_drv_pcmcia_remove(&dev->dev);
}
static int pxa2xx_drv_pcmcia_suspend(struct platform_device *dev, pm_message_t state)
{
return pcmcia_socket_dev_suspend(&dev->dev, state);
}
static int pxa2xx_drv_pcmcia_resume(struct platform_device *dev)
{
pxa2xx_configure_sockets(&dev->dev);
return pcmcia_socket_dev_resume(&dev->dev);
}
static struct platform_driver pxa2xx_pcmcia_driver = {
.probe = pxa2xx_drv_pcmcia_probe,
.remove = pxa2xx_drv_pcmcia_remove,
.suspend = pxa2xx_drv_pcmcia_suspend,
.resume = pxa2xx_drv_pcmcia_resume,
.driver = {
.name = "pxa2xx-pcmcia",
.owner = THIS_MODULE,
},
};
static int __init pxa2xx_pcmcia_init(void)
{
return platform_driver_register(&pxa2xx_pcmcia_driver);
}
static void __exit pxa2xx_pcmcia_exit(void)
{
platform_driver_unregister(&pxa2xx_pcmcia_driver);
}
fs_initcall(pxa2xx_pcmcia_init);
module_exit(pxa2xx_pcmcia_exit);
MODULE_AUTHOR("Stefan Eletzhofer <stefan.eletzhofer@inquant.de> and Ian Molton <spyro@f2s.com>");
MODULE_DESCRIPTION("Linux PCMCIA Card Services: PXA2xx core socket driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pxa2xx-pcmcia");
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