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
sa1100_generic.c
/*======================================================================
Device driver for the PCMCIA control functionality of StrongARM
SA-1100 microprocessors.
The contents of this file are subject to the Mozilla Public
License Version 1.1 (the "License"); you may not use this file
except in compliance with the License. You may obtain a copy of
the License at http://www.mozilla.org/MPL/
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
The initial developer of the original code is John G. Dorsey
<john+@cs.cmu.edu>. Portions created by John G. Dorsey are
Copyright (C) 1999 John G. Dorsey. All Rights Reserved.
Alternatively, the contents of this file may be used under the
terms of the GNU Public License version 2 (the "GPL"), in which
case the provisions of the GPL are applicable instead of the
above. If you wish to allow the use of your version of this file
only under the terms of the GPL and not to allow others to use
your version of this file under the MPL, indicate your decision
by deleting the provisions above and replace them with the notice
and other provisions required by the GPL. If you do not delete
the provisions above, a recipient may use your version of this
file under either the MPL or the GPL.
======================================================================*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <pcmcia/cs_types.h>
#include <pcmcia/cs.h>
#include <pcmcia/ss.h>
#include <asm/hardware/scoop.h>
#include "sa1100_generic.h"
int __init pcmcia_collie_init(struct device *dev);
static int (*sa11x0_pcmcia_hw_init[])(struct device *dev) = {
#ifdef CONFIG_SA1100_ASSABET
pcmcia_assabet_init,
#endif
#ifdef CONFIG_SA1100_CERF
pcmcia_cerf_init,
#endif
#ifdef CONFIG_SA1100_H3600
pcmcia_h3600_init,
#endif
#ifdef CONFIG_SA1100_SHANNON
pcmcia_shannon_init,
#endif
#ifdef CONFIG_SA1100_SIMPAD
pcmcia_simpad_init,
#endif
#ifdef CONFIG_SA1100_COLLIE
pcmcia_collie_init,
#endif
};
static int sa11x0_drv_pcmcia_probe(struct platform_device *dev)
{
int i, ret = -ENODEV;
/*
* Initialise any "on-board" PCMCIA sockets.
*/
for (i = 0; i < ARRAY_SIZE(sa11x0_pcmcia_hw_init); i++) {
ret = sa11x0_pcmcia_hw_init[i](&dev->dev);
if (ret == 0)
break;
}
return ret;
}
static int sa11x0_drv_pcmcia_remove(struct platform_device *dev)
{
return soc_common_drv_pcmcia_remove(&dev->dev);
}
static int sa11x0_drv_pcmcia_suspend(struct platform_device *dev,
pm_message_t state)
{
return pcmcia_socket_dev_suspend(&dev->dev, state);
}
static int sa11x0_drv_pcmcia_resume(struct platform_device *dev)
{
return pcmcia_socket_dev_resume(&dev->dev);
}
static struct platform_driver sa11x0_pcmcia_driver = {
.driver = {
.name = "sa11x0-pcmcia",
.owner = THIS_MODULE,
},
.probe = sa11x0_drv_pcmcia_probe,
.remove = sa11x0_drv_pcmcia_remove,
.suspend = sa11x0_drv_pcmcia_suspend,
.resume = sa11x0_drv_pcmcia_resume,
};
/* sa11x0_pcmcia_init()
* ^^^^^^^^^^^^^^^^^^^^
*
* This routine performs low-level PCMCIA initialization and then
* registers this socket driver with Card Services.
*
* Returns: 0 on success, -ve error code on failure
*/
static int __init sa11x0_pcmcia_init(void)
{
return platform_driver_register(&sa11x0_pcmcia_driver);
}
/* sa11x0_pcmcia_exit()
* ^^^^^^^^^^^^^^^^^^^^
* Invokes the low-level kernel service to free IRQs associated with this
* socket controller and reset GPIO edge detection.
*/
static void __exit sa11x0_pcmcia_exit(void)
{
platform_driver_unregister(&sa11x0_pcmcia_driver);
}
MODULE_AUTHOR("John Dorsey <john+@cs.cmu.edu>");
MODULE_DESCRIPTION("Linux PCMCIA Card Services: SA-11x0 Socket Controller");
MODULE_LICENSE("Dual MPL/GPL");
fs_initcall(sa11x0_pcmcia_init);
module_exit(sa11x0_pcmcia_exit);
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