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-rw-r--r--Documentation/sysctl/vm.txt11
-rw-r--r--Documentation/vm/balance18
2 files changed, 15 insertions, 14 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 6fab2dcbb4d3..0ea5adbc5b16 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -233,8 +233,8 @@ These protections are added to score to judge whether this zone should be used
233for page allocation or should be reclaimed. 233for page allocation or should be reclaimed.
234 234
235In this example, if normal pages (index=2) are required to this DMA zone and 235In this example, if normal pages (index=2) are required to this DMA zone and
236pages_high is used for watermark, the kernel judges this zone should not be 236watermark[WMARK_HIGH] is used for watermark, the kernel judges this zone should
237used because pages_free(1355) is smaller than watermark + protection[2] 237not be used because pages_free(1355) is smaller than watermark + protection[2]
238(4 + 2004 = 2008). If this protection value is 0, this zone would be used for 238(4 + 2004 = 2008). If this protection value is 0, this zone would be used for
239normal page requirement. If requirement is DMA zone(index=0), protection[0] 239normal page requirement. If requirement is DMA zone(index=0), protection[0]
240(=0) is used. 240(=0) is used.
@@ -280,9 +280,10 @@ The default value is 65536.
280min_free_kbytes: 280min_free_kbytes:
281 281
282This is used to force the Linux VM to keep a minimum number 282This is used to force the Linux VM to keep a minimum number
283of kilobytes free. The VM uses this number to compute a pages_min 283of kilobytes free. The VM uses this number to compute a
284value for each lowmem zone in the system. Each lowmem zone gets 284watermark[WMARK_MIN] value for each lowmem zone in the system.
285a number of reserved free pages based proportionally on its size. 285Each lowmem zone gets a number of reserved free pages based
286proportionally on its size.
286 287
287Some minimal amount of memory is needed to satisfy PF_MEMALLOC 288Some minimal amount of memory is needed to satisfy PF_MEMALLOC
288allocations; if you set this to lower than 1024KB, your system will 289allocations; if you set this to lower than 1024KB, your system will
diff --git a/Documentation/vm/balance b/Documentation/vm/balance
index bd3d31bc4915..c46e68cf9344 100644
--- a/Documentation/vm/balance
+++ b/Documentation/vm/balance
@@ -75,15 +75,15 @@ Page stealing from process memory and shm is done if stealing the page would
75alleviate memory pressure on any zone in the page's node that has fallen below 75alleviate memory pressure on any zone in the page's node that has fallen below
76its watermark. 76its watermark.
77 77
78pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are 78watemark[WMARK_MIN/WMARK_LOW/WMARK_HIGH]/low_on_memory/zone_wake_kswapd: These
79per-zone fields, used to determine when a zone needs to be balanced. When 79are per-zone fields, used to determine when a zone needs to be balanced. When
80the number of pages falls below pages_min, the hysteric field low_on_memory 80the number of pages falls below watermark[WMARK_MIN], the hysteric field
81gets set. This stays set till the number of free pages becomes pages_high. 81low_on_memory gets set. This stays set till the number of free pages becomes
82When low_on_memory is set, page allocation requests will try to free some 82watermark[WMARK_HIGH]. When low_on_memory is set, page allocation requests will
83pages in the zone (providing GFP_WAIT is set in the request). Orthogonal 83try to free some pages in the zone (providing GFP_WAIT is set in the request).
84to this, is the decision to poke kswapd to free some zone pages. That 84Orthogonal to this, is the decision to poke kswapd to free some zone pages.
85decision is not hysteresis based, and is done when the number of free 85That decision is not hysteresis based, and is done when the number of free
86pages is below pages_low; in which case zone_wake_kswapd is also set. 86pages is below watermark[WMARK_LOW]; in which case zone_wake_kswapd is also set.
87 87
88 88
89(Good) Ideas that I have heard: 89(Good) Ideas that I have heard: