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74d3694433
linux_dsm_epyc7002/mm
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Howard Cochran 74d3694433 writeback: Fix performance regression in wb_over_bg_thresh() 
Commit 947e9762a8 ("writeback: update wb_over_bg_thresh() to use
wb_domain aware operations") unintentionally changed this function's
meaning from "are there more dirty pages than the background writeback
threshold" to "are there more dirty pages than the writeback threshold".
The background writeback threshold is typically half of the writeback
threshold, so this had the effect of raising the number of dirty pages
required to cause a writeback worker to perform background writeout.

This can cause a very severe performance regression when a BDI uses
BDI_CAP_STRICTLIMIT because balance_dirty_pages() and the writeback worker
can now disagree on whether writeback should be initiated.

For example, in a system having 1GB of RAM, a single spinning disk, and a
"pass-through" FUSE filesystem mounted over the disk, application code
mmapped a 128MB file on the disk and was randomly dirtying pages in that
mapping.

Because FUSE uses strictlimit and has a default max_ratio of only 1%, in
balance_dirty_pages, thresh is ~200, bg_thresh is ~100, and the
dirty_freerun_ceiling is the average of those, ~150. So, it pauses the
dirtying processes when we have 151 dirty pages and wakes up a background
writeback worker. But the worker tests the wrong threshold (200 instead of
100), so it does not initiate writeback and just returns.

Thus, balance_dirty_pages keeps looping, sleeping and then waking up the
worker who will do nothing. It remains stuck in this state until the few
dirty pages that we have finally expire and we write them back for that
reason. Then the whole process repeats, resulting in near-zero throughput
through the FUSE BDI.

The fix is to call the parameterized variant of wb_calc_thresh, so that the
worker will do writeback if the bg_thresh is exceeded which was the
behavior before the referenced commit.

Fixes: 947e9762a8 ("writeback: update wb_over_bg_thresh() to use wb_domain aware operations")
Signed-off-by: Howard Cochran <hcochran@kernelspring.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2+
Tested-by Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-05-05 15:44:55 -06:00
..
kasan mm, kasan: stackdepot implementation. Enable stackdepot for SLAB 2016-03-25 16:37:42 -07:00
backing-dev.c writeback: fix the wrong congested state variable definition 2016-03-31 12:26:25 -06:00
balloon_compaction.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-03-17 21:38:27 -07:00
bootmem.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
cleancache.c cleancache: constify cleancache_ops structure 2016-01-27 09:09:57 -05:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
cma.c mm/cma.c: suppress warning 2015-11-05 19:34:48 -08:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
compaction.c mm, kswapd: replace kswapd compaction with waking up kcompactd 2016-03-17 15:09:34 -07:00
debug_page_ref.c mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
debug.c mm: introduce page reference manipulation functions 2016-03-17 15:09:34 -07:00
dmapool.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c writeback: implement and use inode_congested() 2015-06-02 08:33:35 -06:00
failslab.c mm: fault-inject take over bootstrap kmem_cache check 2016-03-15 16:55:16 -07:00
filemap.c mm/filemap: generic_file_read_iter(): check for zero reads unconditionally 2016-03-25 16:37:42 -07:00
frame_vector.c mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm 2016-02-16 10:11:12 +01:00
frontswap.c frontswap: allow multiple backends 2015-06-24 17:49:45 -07:00
gup.c mm/core, x86/mm/pkeys: Differentiate instruction fetches 2016-02-18 19:46:29 +01:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c thp: fix typo in khugepaged_scan_pmd() 2016-03-25 16:37:42 -07:00
hugetlb_cgroup.c mm: make compound_head() robust 2015-11-06 17:50:42 -08:00
hugetlb.c mm: convert pr_warning to pr_warn 2016-03-17 15:09:34 -07:00
hwpoison-inject.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h mm, oom: introduce oom reaper 2016-03-25 16:37:42 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
Kconfig Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
Kconfig.debug mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
kmemcheck.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak-test.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
ksm.c mm/core: Do not enforce PKEY permissions on remote mm access 2016-02-18 19:46:28 +01:00
list_lru.c mm: memcontrol: move kmem accounting code to CONFIG_MEMCG 2016-01-20 17:09:18 -08:00
maccess.c mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe 2015-11-05 19:34:48 -08:00
madvise.c mm/madvise: update comment on sys_madvise() 2016-03-15 16:55:16 -07:00
Makefile mm, kasan: SLAB support 2016-03-25 16:37:42 -07:00
memblock.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
memcontrol.c mm: memcontrol: zap oom_info_lock 2016-03-17 15:09:34 -07:00
memory_hotplug.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
memory-failure.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
memory.c mm, oom: introduce oom reaper 2016-03-25 16:37:42 -07:00
mempolicy.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
mempool.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c mm: make remove_migration_ptes() beyond mm/migration.c 2016-03-17 15:09:34 -07:00
mincore.c thp: change pmd_trans_huge_lock() interface to return ptl 2016-01-21 17:20:51 -08:00
mlock.c mm: fix mlock accouting 2016-01-21 17:20:51 -08:00
mm_init.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
mmap.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
mmzone.c mm/mmzone.c: memmap_valid_within() can be boolean 2016-01-14 16:00:49 -08:00
mprotect.c mm/mprotect.c: don't imply PROT_EXEC on non-exec fs 2016-03-22 15:36:02 -07:00
mremap.c mm: cleanup *pte_alloc* interfaces 2016-03-17 15:09:34 -07:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
nommu.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
oom_kill.c oom, oom_reaper: protect oom_reaper_list using simpler way 2016-03-25 16:37:42 -07:00
page_alloc.c mm/page_alloc: prevent merging between isolated and other pageblocks 2016-03-25 16:37:42 -07:00
page_counter.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
page_ext.c mm/page_poisoning.c: allow for zero poisoning 2016-03-15 16:55:16 -07:00
page_idle.c mm: add page_check_address_transhuge() helper 2016-01-15 17:56:32 -08:00
page_io.c zram: revive swap_slot_free_notify 2016-03-22 15:36:02 -07:00
page_isolation.c mm/page_isolation: do some cleanup in "undo_isolate_page_range" 2016-01-15 17:56:32 -08:00
page_owner.c mm: coalesce split strings 2016-03-17 15:09:34 -07:00
page_poison.c mm/page_poisoning.c: allow for zero poisoning 2016-03-15 16:55:16 -07:00
page-writeback.c writeback: Fix performance regression in wb_over_bg_thresh() 2016-05-05 15:44:55 -06:00
pagewalk.c thp: rename split_huge_page_pmd() to split_huge_pmd() 2016-01-15 17:56:32 -08:00
percpu-km.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
pgtable-generic.c mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range 2016-03-17 15:09:34 -07:00
process_vm_access.c mm/gup: Introduce get_user_pages_remote() 2016-02-16 10:04:09 +01:00
quicklist.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
readahead.c mm: move lru_to_page to mm_inline.h 2016-01-14 16:00:49 -08:00
rmap.c thp: rewrite freeze_page()/unfreeze_page() with generic rmap walkers 2016-03-17 15:09:34 -07:00
shmem.c radix-tree,shmem: introduce radix_tree_iter_next() 2016-03-17 15:09:34 -07:00
slab_common.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
slab.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
slab.h mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
slob.c mm: slab: free kmem_cache_node after destroy sysfs file 2016-02-18 16:23:24 -08:00
slub.c mm, kasan: add GFP flags to KASAN API 2016-03-25 16:37:42 -07:00
sparse-vmemmap.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
sparse.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap_cgroup.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap_state.c mm: memcontrol: charge swap to cgroup2 2016-01-20 17:09:18 -08:00
swap.c mm, x86: get_user_pages() for dax mappings 2016-01-15 17:56:32 -08:00
swapfile.c Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2016-03-21 13:48:00 -07:00
truncate.c mm: remove unnecessary uses of lock_page_memcg() 2016-03-15 16:55:16 -07:00
userfaultfd.c mm: cleanup *pte_alloc* interfaces 2016-03-17 15:09:34 -07:00
util.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 19:08:56 -07:00
vmacache.c mm/vmacache: inline vmacache_valid_mm() 2015-11-05 19:34:48 -08:00
vmalloc.c mm/vmalloc: use PAGE_ALIGNED() to check PAGE_SIZE alignment 2016-03-17 15:09:34 -07:00
vmpressure.c mm/vmpressure.c: fix subtree pressure detection 2016-02-03 08:28:43 -08:00
vmscan.c mm: introduce page reference manipulation functions 2016-03-17 15:09:34 -07:00
vmstat.c thp, vmstats: count deferred split events 2016-03-17 15:09:34 -07:00
workingset.c mm: workingset: make shadow node shrinker memcg aware 2016-03-17 15:09:34 -07:00
zbud.c mm/zbud.c: use list_last_entry() instead of list_tail_entry() 2016-01-15 11:40:52 -08:00
zpool.c mm: zsmalloc: constify struct zs_pool name 2015-11-06 17:50:42 -08:00
zsmalloc.c mm/zsmalloc: add `freeable' column to pool stat 2016-03-17 15:09:34 -07:00
zswap.c mm/zswap: change incorrect strncmp use to strcmp 2015-12-18 14:25:40 -08:00