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What is the problem?
Yes, Linux Does Bad In Low RAM / Memory Pressure Situations On The Desktop
The solution:
[PATCH] Protect clean file pages under memory pressure to prevent thrashing, avoid high latency and prevent livelock in near-OOM conditions
Success story with this patch: https://notes.valdikss.org.ru/linux-...-from-2007/en/
The patches provide sysctl knobs for protecting the specified amount of clean file pages (CFP) under memory pressure.
The kernel does not have a mechanism for selectively protecting clean file pages. A certain amount of the CFP is required by the userspace for normal operation. First of all, you need a cache of shared libraries and executable files. If the volume of the CFP cache falls below a certain level, thrashing and even livelock occurs.
Protection of CFP may be used to prevent thrashing and reducing I/O under memory pressure. Hard protection of CFP may be used to avoid high latency and prevent livelock in near-OOM conditions. The patch provides sysctl knobs for protecting the specified amount of clean file cache under memory pressure.
The vm.clean_low_kbytes sysctl knob provides best-effort protection of CFP. The CFP on the current node won't be reclaimed uder memory pressure when their amount is below vm.clean_low_kbytes unless we threaten to OOM or have no free swap space or vm.swappiness=0. Setting it to a high value may result in a early eviction of anonymous pages into the swap space by attempting to hold the protected amount of clean file pages in memory. The default value is defined by CONFIG_CLEAN_LOW_KBYTES.
The vm.clean_min_kbytes sysctl knob provides hard protection of CFP. The CFP on the current node won't be reclaimed under memory pressure when their amount is below vm.clean_min_kbytes. Setting it to a high value may result in a early out-of-memory condition due to the inability to reclaim the protected amount of CFP when other types of pages cannot be reclaimed. The default value is defined by CONFIG_CLEAN_MIN_KBYTES.
Any questions are welcome.
Yes, Linux Does Bad In Low RAM / Memory Pressure Situations On The Desktop
The solution:
[PATCH] Protect clean file pages under memory pressure to prevent thrashing, avoid high latency and prevent livelock in near-OOM conditions
Success story with this patch: https://notes.valdikss.org.ru/linux-...-from-2007/en/
The patches provide sysctl knobs for protecting the specified amount of clean file pages (CFP) under memory pressure.
The kernel does not have a mechanism for selectively protecting clean file pages. A certain amount of the CFP is required by the userspace for normal operation. First of all, you need a cache of shared libraries and executable files. If the volume of the CFP cache falls below a certain level, thrashing and even livelock occurs.
Protection of CFP may be used to prevent thrashing and reducing I/O under memory pressure. Hard protection of CFP may be used to avoid high latency and prevent livelock in near-OOM conditions. The patch provides sysctl knobs for protecting the specified amount of clean file cache under memory pressure.
The vm.clean_low_kbytes sysctl knob provides best-effort protection of CFP. The CFP on the current node won't be reclaimed uder memory pressure when their amount is below vm.clean_low_kbytes unless we threaten to OOM or have no free swap space or vm.swappiness=0. Setting it to a high value may result in a early eviction of anonymous pages into the swap space by attempting to hold the protected amount of clean file pages in memory. The default value is defined by CONFIG_CLEAN_LOW_KBYTES.
The vm.clean_min_kbytes sysctl knob provides hard protection of CFP. The CFP on the current node won't be reclaimed under memory pressure when their amount is below vm.clean_min_kbytes. Setting it to a high value may result in a early out-of-memory condition due to the inability to reclaim the protected amount of CFP when other types of pages cannot be reclaimed. The default value is defined by CONFIG_CLEAN_MIN_KBYTES.
Any questions are welcome.
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