kernel_optimize_test/mm
Richard Kennedy d7831a0bdf mm: prevent balance_dirty_pages() from doing too much work
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>
2009-06-30 18:56:01 -07:00
..
allocpercpu.c percpu: __percpu_depopulate_mask can take a const mask 2009-04-06 13:44:15 -07:00
backing-dev.c block: change the request allocation/congestion logic to be sync/async based 2009-04-06 08:04:53 -07:00
bootmem.c bootmem.c: avoid c90 declaration warning 2009-06-19 16:46:04 -07:00
bounce.c block: remove some includings of blktrace_api.h 2009-06-16 11:19:36 +02:00
debug-pagealloc.c generic debug pagealloc 2009-04-01 08:59:13 -07:00
dmapool.c dmapools: protect page_list walk in show_pools() 2009-06-30 18:56:00 -07:00
fadvise.c readahead: move max_sane_readahead() calls into force_page_cache_readahead() 2009-06-16 19:47:28 -07:00
failslab.c kmemtrace, mm: fix slab.h dependency problem in mm/failslab.c 2009-04-03 12:23:01 +02:00
filemap_xip.c mm: do_xip_mapping_read: fix length calculation 2009-04-02 19:04:49 -07:00
filemap.c page allocator: do not check NUMA node ID when the caller knows the node is valid 2009-06-16 19:47:32 -07:00
fremap.c Do not account for the address space used by hugetlbfs using VM_ACCOUNT 2009-02-10 10:48:42 -08:00
highmem.c block: remove some includings of blktrace_api.h 2009-06-16 11:19:36 +02:00
hugetlb.c hugetlb: fault flags instead of write_access 2009-06-23 11:23:33 -07:00
init-mm.c mm: consolidate init_mm definition 2009-06-16 19:47:28 -07:00
internal.h vmscan: do not unconditionally treat zones that fail zone_reclaim() as full 2009-06-16 19:47:45 -07:00
Kconfig Merge branch 'akpm' 2009-06-16 19:50:13 -07:00
Kconfig.debug kmemcheck: enable in the x86 Kconfig 2009-06-15 15:49:15 +02:00
kmemcheck.c kmemcheck: add hooks for the page allocator 2009-06-15 15:48:33 +02:00
kmemleak-test.c kmemleak: Simple testing module for kmemleak 2009-06-11 17:04:19 +01:00
kmemleak.c kmemleak: use pr_fmt 2009-06-23 14:40:26 +01:00
maccess.c [S390] maccess: add weak attribute to probe_kernel_write 2009-06-12 10:27:37 +02:00
madvise.c mm: madvise(): correct return code 2009-06-16 19:47:40 -07:00
Makefile Merge branch 'akpm' 2009-06-16 19:50:13 -07:00
memcontrol.c memcg: fix lru rotation in isolate_pages 2009-06-18 13:03:48 -07:00
memory_hotplug.c page-allocator: reset wmark_min and inactive ratio of zone when hotplug happens 2009-06-16 19:47:42 -07:00
memory.c clarify get_user_pages() prototype 2009-06-25 11:22:13 -07:00
mempolicy.c page allocator: do not check NUMA node ID when the caller knows the node is valid 2009-06-16 19:47:32 -07:00
mempool.c
migrate.c migration: only migrate_prep() once per move_pages() 2009-06-16 19:47:41 -07:00
mincore.c [CVE-2009-0029] System call wrappers part 14 2009-01-14 14:15:24 +01:00
mlock.c mm: remove CONFIG_UNEVICTABLE_LRU config option 2009-06-16 19:47:42 -07:00
mm_init.c
mmap.c Merge branch 'perfcounters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-11 14:01:07 -07:00
mmu_notifier.c
mmzone.c [ARM] Double check memmap is actually valid with a memmap has unexpected holes V2 2009-05-18 11:22:24 +01:00
mprotect.c perf_counter: Add mmap event hooks to mprotect() 2009-06-08 23:10:43 +02:00
mremap.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
msync.c [CVE-2009-0029] System call wrappers part 13 2009-01-14 14:15:23 +01:00
nommu.c clarify get_user_pages() prototype 2009-06-25 11:22:13 -07:00
oom_kill.c oom: only oom kill exiting tasks with attached memory 2009-06-16 19:47:45 -07:00
page_alloc.c Don't warn about order-1 allocations with __GFP_NOFAIL 2009-06-24 12:16:49 -07:00
page_cgroup.c memcg: remove some redundant checks 2009-06-18 13:03:47 -07:00
page_io.c mm: remove file argument from swap_readpage() 2009-06-16 19:47:44 -07:00
page_isolation.c
page-writeback.c mm: prevent balance_dirty_pages() from doing too much work 2009-06-30 18:56:01 -07:00
pagewalk.c
pdflush.c Revert "mm: add /proc controls for pdflush threads" 2009-05-15 11:32:24 +02:00
percpu.c x86: implement percpu_alloc kernel parameter 2009-06-22 11:56:24 +09:00
prio_tree.c
quicklist.c cpumask: replace node_to_cpumask with cpumask_of_node. 2009-03-13 14:49:46 +10:30
readahead.c readahead: introduce context readahead algorithm 2009-06-16 19:47:30 -07:00
rmap.c memcg: add file-based RSS accounting 2009-06-18 13:03:47 -07:00
shmem_acl.c switch shmem to inode->i_acl 2009-06-24 08:17:06 -04:00
shmem.c Get "no acls for this inode" right, fix shmem breakage 2009-06-24 16:58:48 -04:00
slab.c mm: Extend gfp masking to the page allocator 2009-06-18 13:12:57 -07:00
slob.c Merge branches 'slab/documentation', 'slab/fixes', 'slob/cleanups' and 'slub/fixes' into for-linus 2009-06-17 08:30:15 +03:00
slub.c SLUB: Don't pass __GFP_FAIL for the initial allocation 2009-06-24 12:20:14 -07:00
sparse-vmemmap.c
sparse.c mm: mminit_validate_memmodel_limits(): remove redundant test 2009-04-01 08:59:11 -07:00
swap_state.c mm: remove file argument from swap_readpage() 2009-06-16 19:47:44 -07:00
swap.c mm: fix Committed_AS underflow on large NR_CPUS environment 2009-05-02 15:36:10 -07:00
swapfile.c memcg: fix swap accounting 2009-06-18 13:03:47 -07:00
thrash.c mm: pass mm to grab_swap_token 2009-06-23 12:50:05 -07:00
truncate.c mm: remove __invalidate_mapping_pages variant 2009-06-16 19:47:43 -07:00
util.c Merge branches 'slab/documentation', 'slab/fixes', 'slob/cleanups' and 'slub/fixes' into for-linus 2009-06-17 08:30:15 +03:00
vmalloc.c Merge branch 'for-linus' of git://linux-arm.org/linux-2.6 2009-06-11 14:15:57 -07:00
vmscan.c mm: fix incorrect page removal from LRU 2009-06-23 10:17:28 -07:00
vmstat.c vmscan: count the number of times zone_reclaim() scans and fails 2009-06-16 19:47:46 -07:00