IB/ipath: Fix IB compliance problems with link state vs physical state

[linux-2.6-omap-h63xx.git] / Documentation / filesystems / proc.txt

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 0b1b0c0086137c6bb07a1f220ccb6df7d31832b6..5681e2fa1496167e6f876b6dab39e9605597a117 100644 (file)
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -1029,6 +1029,14 @@ nr_inodes
 Denotes the  number  of  inodes the system has allocated. This number will
 grow and shrink dynamically.
 
 Denotes the  number  of  inodes the system has allocated. This number will
 grow and shrink dynamically.
 

+nr_open
+-------
+
+Denotes the maximum number of file-handles a process can
+allocate. Default value is 1024*1024 (1048576) which should be
+enough for most machines. Actual limit depends on RLIMIT_NOFILE
+resource limit.
+

 nr_free_inodes
 --------------
 
 nr_free_inodes
 --------------
 


@@ -1315,13 +1323,28 @@ for writeout by the pdflush daemons.  It is expressed in 100'ths of a second.
 Data which has been dirty in-memory for longer than this interval will be
 written out next time a pdflush daemon wakes up.
 
 Data which has been dirty in-memory for longer than this interval will be
 written out next time a pdflush daemon wakes up.
 

+highmem_is_dirtyable
+--------------------
+
+Only present if CONFIG_HIGHMEM is set.
+
+This defaults to 0 (false), meaning that the ratios set above are calculated
+as a percentage of lowmem only.  This protects against excessive scanning
+in page reclaim, swapping and general VM distress.
+
+Setting this to 1 can be useful on 32 bit machines where you want to make
+random changes within an MMAPed file that is larger than your available
+lowmem without causing large quantities of random IO.  Is is safe if the
+behavior of all programs running on the machine is known and memory will
+not be otherwise stressed.
+

 legacy_va_layout
 ----------------
 
 If non-zero, this sysctl disables the new 32-bit mmap mmap layout - the kernel
 will use the legacy (2.4) layout for all processes.
 
 legacy_va_layout
 ----------------
 
 If non-zero, this sysctl disables the new 32-bit mmap mmap layout - the kernel
 will use the legacy (2.4) layout for all processes.
 

-lower_zone_protection
+lowmem_reserve_ratio

 ---------------------
 
 For some specialised workloads on highmem machines it is dangerous for
 ---------------------
 
 For some specialised workloads on highmem machines it is dangerous for


@@ -1341,25 +1364,71 @@ captured into pinned user memory.
 mechanism will also defend that region from allocations which could use
 highmem or lowmem).
 
 mechanism will also defend that region from allocations which could use
 highmem or lowmem).
 

-The `lower_zone_protection' tunable determines how aggressive the kernel is
-in defending these lower zones.  The default value is zero - no
-protection at all.
+The `lowmem_reserve_ratio' tunable determines how aggressive the kernel is
+in defending these lower zones.

 
 If you have a machine which uses highmem or ISA DMA and your
 applications are using mlock(), or if you are running with no swap then
 
 If you have a machine which uses highmem or ISA DMA and your
 applications are using mlock(), or if you are running with no swap then

-you probably should increase the lower_zone_protection setting.
-
-The units of this tunable are fairly vague.  It is approximately equal
-to "megabytes," so setting lower_zone_protection=100 will protect around 100
-megabytes of the lowmem zone from user allocations.  It will also make
-those 100 megabytes unavailable for use by applications and by
-pagecache, so there is a cost.
-
-The effects of this tunable may be observed by monitoring
-/proc/meminfo:LowFree.  Write a single huge file and observe the point
-at which LowFree ceases to fall.
-
-A reasonable value for lower_zone_protection is 100.
+you probably should change the lowmem_reserve_ratio setting.
+
+The lowmem_reserve_ratio is an array. You can see them by reading this file.
+-
+% cat /proc/sys/vm/lowmem_reserve_ratio
+256     256     32
+-
+Note: # of this elements is one fewer than number of zones. Because the highest
+      zone's value is not necessary for following calculation.
+
+But, these values are not used directly. The kernel calculates # of protection
+pages for each zones from them. These are shown as array of protection pages
+in /proc/zoneinfo like followings. (This is an example of x86-64 box).
+Each zone has an array of protection pages like this.
+
+-
+Node 0, zone      DMA
+  pages free     1355
+        min      3
+        low      3
+        high     4
+       :
+       :
+    numa_other   0
+        protection: (0, 2004, 2004, 2004)
+       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  pagesets
+    cpu: 0 pcp: 0
+        :
+-
+These protections are added to score to judge whether this zone should be used
+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]
+(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.
+
+zone[i]'s protection[j] is calculated by following exprssion.
+
+(i < j):
+  zone[i]->protection[j]
+  = (total sums of present_pages from zone[i+1] to zone[j] on the node)
+    / lowmem_reserve_ratio[i];
+(i = j):
+   (should not be protected. = 0;
+(i > j):
+   (not necessary, but looks 0)
+
+The default values of lowmem_reserve_ratio[i] are
+    256 (if zone[i] means DMA or DMA32 zone)
+    32  (others).
+As above expression, they are reciprocal number of ratio.
+256 means 1/256. # of protection pages becomes about "0.39%" of total present
+pages of higher zones on the node.
+
+If you would like to protect more pages, smaller values are effective.
+The minimum value is 1 (1/1 -> 100%).

 
 page-cluster
 ------------
 
 page-cluster
 ------------