diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/sysctl/vm.txt | 11 | ||||
-rw-r--r-- | Documentation/vm/balance | 18 |
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 | |||
233 | for page allocation or should be reclaimed. | 233 | for page allocation or should be reclaimed. |
234 | 234 | ||
235 | In this example, if normal pages (index=2) are required to this DMA zone and | 235 | In this example, if normal pages (index=2) are required to this DMA zone and |
236 | pages_high is used for watermark, the kernel judges this zone should not be | 236 | watermark[WMARK_HIGH] is used for watermark, the kernel judges this zone should |
237 | used because pages_free(1355) is smaller than watermark + protection[2] | 237 | not 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 |
239 | normal page requirement. If requirement is DMA zone(index=0), protection[0] | 239 | normal 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. | |||
280 | min_free_kbytes: | 280 | min_free_kbytes: |
281 | 281 | ||
282 | This is used to force the Linux VM to keep a minimum number | 282 | This is used to force the Linux VM to keep a minimum number |
283 | of kilobytes free. The VM uses this number to compute a pages_min | 283 | of kilobytes free. The VM uses this number to compute a |
284 | value for each lowmem zone in the system. Each lowmem zone gets | 284 | watermark[WMARK_MIN] value for each lowmem zone in the system. |
285 | a number of reserved free pages based proportionally on its size. | 285 | Each lowmem zone gets a number of reserved free pages based |
286 | proportionally on its size. | ||
286 | 287 | ||
287 | Some minimal amount of memory is needed to satisfy PF_MEMALLOC | 288 | Some minimal amount of memory is needed to satisfy PF_MEMALLOC |
288 | allocations; if you set this to lower than 1024KB, your system will | 289 | allocations; 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 | |||
75 | alleviate memory pressure on any zone in the page's node that has fallen below | 75 | alleviate memory pressure on any zone in the page's node that has fallen below |
76 | its watermark. | 76 | its watermark. |
77 | 77 | ||
78 | pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are | 78 | watemark[WMARK_MIN/WMARK_LOW/WMARK_HIGH]/low_on_memory/zone_wake_kswapd: These |
79 | per-zone fields, used to determine when a zone needs to be balanced. When | 79 | are per-zone fields, used to determine when a zone needs to be balanced. When |
80 | the number of pages falls below pages_min, the hysteric field low_on_memory | 80 | the number of pages falls below watermark[WMARK_MIN], the hysteric field |
81 | gets set. This stays set till the number of free pages becomes pages_high. | 81 | low_on_memory gets set. This stays set till the number of free pages becomes |
82 | When low_on_memory is set, page allocation requests will try to free some | 82 | watermark[WMARK_HIGH]. When low_on_memory is set, page allocation requests will |
83 | pages in the zone (providing GFP_WAIT is set in the request). Orthogonal | 83 | try to free some pages in the zone (providing GFP_WAIT is set in the request). |
84 | to this, is the decision to poke kswapd to free some zone pages. That | 84 | Orthogonal to this, is the decision to poke kswapd to free some zone pages. |
85 | decision is not hysteresis based, and is done when the number of free | 85 | That decision is not hysteresis based, and is done when the number of free |
86 | pages is below pages_low; in which case zone_wake_kswapd is also set. | 86 | pages 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: |