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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sa1111_generic.h
#include "soc_common.h"
#include "sa11xx_base.h"
extern int sa1111_pcmcia_hw_init(struct soc_pcmcia_socket *);
extern void sa1111_pcmcia_hw_shutdown(struct soc_pcmcia_socket *);
extern void sa1111_pcmcia_socket_state(struct soc_pcmcia_socket *, struct pcmcia_state *);
extern int sa1111_pcmcia_configure_socket(struct soc_pcmcia_socket *, const socket_state_t *);
extern void sa1111_pcmcia_socket_init(struct soc_pcmcia_socket *);
extern void sa1111_pcmcia_socket_suspend(struct soc_pcmcia_socket *);
extern int pcmcia_badge4_init(struct device *);
extern int pcmcia_jornada720_init(struct device *);
extern int pcmcia_lubbock_init(struct sa1111_dev *);
extern int pcmcia_neponset_init(struct sa1111_dev *);
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