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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i82092aa.h
#ifndef _INCLUDE_GUARD_i82092aa_H_
#define _INCLUDE_GUARD_i82092aa_H_
#include <linux/interrupt.h>
/* Debuging defines */
#ifdef NOTRACE
#define enter(x) printk("Enter: %s, %s line %i\n",x,__FILE__,__LINE__)
#define leave(x) printk("Leave: %s, %s line %i\n",x,__FILE__,__LINE__)
#define dprintk(fmt, args...) printk(fmt , ## args)
#else
#define enter(x) do {} while (0)
#define leave(x) do {} while (0)
#define dprintk(fmt, args...) do {} while (0)
#endif
/* prototypes */
static int i82092aa_pci_probe(struct pci_dev *dev, const struct pci_device_id *id);
static void i82092aa_pci_remove(struct pci_dev *dev);
static int card_present(int socketno);
static irqreturn_t i82092aa_interrupt(int irq, void *dev);
static int i82092aa_get_status(struct pcmcia_socket *socket, u_int *value);
static int i82092aa_set_socket(struct pcmcia_socket *socket, socket_state_t *state);
static int i82092aa_set_io_map(struct pcmcia_socket *socket, struct pccard_io_map *io);
static int i82092aa_set_mem_map(struct pcmcia_socket *socket, struct pccard_mem_map *mem);
static int i82092aa_init(struct pcmcia_socket *socket);
#endif
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