c4dc4beed2
These patches aim to improve balance_dirty_pages() and directly address three issues: 1) inter device starvation 2) stacked device deadlocks 3) inter process starvation 1 and 2 are a direct result from removing the global dirty limit and using per device dirty limits. By giving each device its own dirty limit is will no longer starve another device, and the cyclic dependancy on the dirty limit is broken. In order to efficiently distribute the dirty limit across the independant devices a floating proportion is used, this will allocate a share of the total limit proportional to the device's recent activity. 3 is done by also scaling the dirty limit proportional to the current task's recent dirty rate. This patch: nfs: remove congestion_end(). It's redundant, clear_bdi_congested() already wakes the waiters. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
111 lines
3.7 KiB
C
111 lines
3.7 KiB
C
/*
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* include/linux/backing-dev.h
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*
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* low-level device information and state which is propagated up through
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* to high-level code.
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*/
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#ifndef _LINUX_BACKING_DEV_H
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#define _LINUX_BACKING_DEV_H
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#include <asm/atomic.h>
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struct page;
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/*
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* Bits in backing_dev_info.state
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*/
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enum bdi_state {
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BDI_pdflush, /* A pdflush thread is working this device */
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BDI_write_congested, /* The write queue is getting full */
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BDI_read_congested, /* The read queue is getting full */
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BDI_unused, /* Available bits start here */
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};
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typedef int (congested_fn)(void *, int);
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struct backing_dev_info {
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unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
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unsigned long state; /* Always use atomic bitops on this */
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unsigned int capabilities; /* Device capabilities */
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congested_fn *congested_fn; /* Function pointer if device is md/dm */
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void *congested_data; /* Pointer to aux data for congested func */
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void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
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void *unplug_io_data;
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};
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/*
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* Flags in backing_dev_info::capability
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* - The first two flags control whether dirty pages will contribute to the
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* VM's accounting and whether writepages() should be called for dirty pages
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* (something that would not, for example, be appropriate for ramfs)
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* - These flags let !MMU mmap() govern direct device mapping vs immediate
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* copying more easily for MAP_PRIVATE, especially for ROM filesystems
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*/
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#define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */
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#define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */
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#define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */
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#define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */
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#define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */
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#define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */
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#define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */
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#define BDI_CAP_VMFLAGS \
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(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
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#if defined(VM_MAYREAD) && \
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(BDI_CAP_READ_MAP != VM_MAYREAD || \
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BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
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BDI_CAP_EXEC_MAP != VM_MAYEXEC)
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#error please change backing_dev_info::capabilities flags
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#endif
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extern struct backing_dev_info default_backing_dev_info;
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void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
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int writeback_acquire(struct backing_dev_info *bdi);
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int writeback_in_progress(struct backing_dev_info *bdi);
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void writeback_release(struct backing_dev_info *bdi);
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static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
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{
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if (bdi->congested_fn)
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return bdi->congested_fn(bdi->congested_data, bdi_bits);
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return (bdi->state & bdi_bits);
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}
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static inline int bdi_read_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, 1 << BDI_read_congested);
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}
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static inline int bdi_write_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, 1 << BDI_write_congested);
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}
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static inline int bdi_rw_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, (1 << BDI_read_congested)|
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(1 << BDI_write_congested));
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}
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void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
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void set_bdi_congested(struct backing_dev_info *bdi, int rw);
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long congestion_wait(int rw, long timeout);
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#define bdi_cap_writeback_dirty(bdi) \
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(!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
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#define bdi_cap_account_dirty(bdi) \
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(!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
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#define mapping_cap_writeback_dirty(mapping) \
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bdi_cap_writeback_dirty((mapping)->backing_dev_info)
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#define mapping_cap_account_dirty(mapping) \
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bdi_cap_account_dirty((mapping)->backing_dev_info)
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#endif /* _LINUX_BACKING_DEV_H */
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