- legacy_va_layout
- lowmem_reserve_ratio
- max_map_count
+- memory_failure_early_kill
+- memory_failure_recovery
- min_free_kbytes
- min_slab_ratio
- min_unmapped_ratio
- nr_hugepages
- nr_overcommit_hugepages
- nr_pdflush_threads
-- nr_pdflush_threads_min
-- nr_pdflush_threads_max
- nr_trim_pages (only if CONFIG_MMU=n)
- numa_zonelist_order
- oom_dump_tasks
- vfs_cache_pressure
- zone_reclaim_mode
-
==============================================================
block_dump
for page allocation or should be reclaimed.
In this example, if normal pages (index=2) are required to this DMA zone and
-pages_high is used for watermark, the kernel judges this zone should not be
-used because pages_free(1355) is smaller than watermark + protection[2]
+watermark[WMARK_HIGH] is used for watermark, the kernel judges this zone should
+not be used because pages_free(1355) is smaller than watermark + protection[2]
(4 + 2004 = 2008). If this protection value is 0, this zone would be used for
normal page requirement. If requirement is DMA zone(index=0), protection[0]
(=0) is used.
The default value is 65536.
+=============================================================
+
+memory_failure_early_kill:
+
+Control how to kill processes when uncorrected memory error (typically
+a 2bit error in a memory module) is detected in the background by hardware
+that cannot be handled by the kernel. In some cases (like the page
+still having a valid copy on disk) the kernel will handle the failure
+transparently without affecting any applications. But if there is
+no other uptodate copy of the data it will kill to prevent any data
+corruptions from propagating.
+
+1: Kill all processes that have the corrupted and not reloadable page mapped
+as soon as the corruption is detected. Note this is not supported
+for a few types of pages, like kernel internally allocated data or
+the swap cache, but works for the majority of user pages.
+
+0: Only unmap the corrupted page from all processes and only kill a process
+who tries to access it.
+
+The kill is done using a catchable SIGBUS with BUS_MCEERR_AO, so processes can
+handle this if they want to.
+
+This is only active on architectures/platforms with advanced machine
+check handling and depends on the hardware capabilities.
+
+Applications can override this setting individually with the PR_MCE_KILL prctl
+
+==============================================================
+
+memory_failure_recovery
+
+Enable memory failure recovery (when supported by the platform)
+
+1: Attempt recovery.
+
+0: Always panic on a memory failure.
+
==============================================================
min_free_kbytes:
This is used to force the Linux VM to keep a minimum number
-of kilobytes free. The VM uses this number to compute a pages_min
-value for each lowmem zone in the system. Each lowmem zone gets
-a number of reserved free pages based proportionally on its size.
+of kilobytes free. The VM uses this number to compute a
+watermark[WMARK_MIN] value for each lowmem zone in the system.
+Each lowmem zone gets a number of reserved free pages based
+proportionally on its size.
Some minimal amount of memory is needed to satisfy PF_MEMALLOC
allocations; if you set this to lower than 1024KB, your system will
This is available only on NUMA kernels.
-A percentage of the total pages in each zone. Zone reclaim will only
-occur if more than this percentage of pages are file backed and unmapped.
-This is to insure that a minimal amount of local pages is still available for
-file I/O even if the node is overallocated.
+This is a percentage of the total pages in each zone. Zone reclaim will
+only occur if more than this percentage of pages are in a state that
+zone_reclaim_mode allows to be reclaimed.
+
+If zone_reclaim_mode has the value 4 OR'd, then the percentage is compared
+against all file-backed unmapped pages including swapcache pages and tmpfs
+files. Otherwise, only unmapped pages backed by normal files but not tmpfs
+files and similar are considered.
The default is 1 percent.
mmap_min_addr
This file indicates the amount of address space which a user process will
-be restricted from mmaping. Since kernel null dereference bugs could
+be restricted from mmapping. Since kernel null dereference bugs could
accidentally operate based on the information in the first couple of pages
of memory userspace processes should not be allowed to write to them. By
default this value is set to 0 and no protections will be enforced by the
The current number of pdflush threads. This value is read-only.
The value changes according to the number of dirty pages in the system.
-When neccessary, additional pdflush threads are created, one per second, up to
+When necessary, additional pdflush threads are created, one per second, up to
nr_pdflush_threads_max.
==============================================================
==============================================================
-nr_pdflush_threads_min
-
-This value controls the minimum number of pdflush threads.
-
-At boot time, the kernel will create and maintain 'nr_pdflush_threads_min'
-threads for the kernel's lifetime.
-
-The default value is 2. The minimum value you can specify is 1, and
-the maximum value is the current setting of 'nr_pdflush_threads_max'.
-
-See 'nr_pdflush_threads_max' below for more information.
-
-==============================================================
-
-nr_pdflush_threads_max
-
-This value controls the maximum number of pdflush threads that can be
-created. The pdflush algorithm will create a new pdflush thread (up to
-this maximum) if no pdflush threads have been available for >= 1 second.
-
-The default value is 8. The minimum value you can specify is the
-current value of 'nr_pdflush_threads_min' and the
-maximum is 1000.
-
-==============================================================
-
overcommit_memory:
This value contains a flag that enables memory overcommitment.
This control is used to define how aggressive the kernel will swap
memory pages. Higher values will increase agressiveness, lower values
-descrease the amount of swap.
+decrease the amount of swap.
The default value is 60.
At the default value of vfs_cache_pressure=100 the kernel will attempt to
reclaim dentries and inodes at a "fair" rate with respect to pagecache and
swapcache reclaim. Decreasing vfs_cache_pressure causes the kernel to prefer
-to retain dentry and inode caches. Increasing vfs_cache_pressure beyond 100
+to retain dentry and inode caches. When vfs_cache_pressure=0, the kernel will
+never reclaim dentries and inodes due to memory pressure and this can easily
+lead to out-of-memory conditions. Increasing vfs_cache_pressure beyond 100
causes the kernel to prefer to reclaim dentries and inodes.
==============================================================
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff