How to force the kernel to always maintain at least some page cache?

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Is there any way to force the kernel to always maintain at least some page cache for writeback caching purposes, even when faced with memory pressure?



I have a rather special use case, where swapping to zswap is much more preferable than not having a large page cache. (I have set the relevant vm.dirty values to allow a lot of write caching)



So what I would like, is set a minimum page cache size (say 10-30% of total RAM), and if memory usage rises, instead of flushing dirty pages, the kernel should start swapping (I am using zswap, so that would just mean compressing pages, but still keeping most of them in RAM)



I have tried raising vm.swappiness to 100, and lowering vm.vfs_cache_pressure to 10, but this does not seem to have cut it.






memory swap cache virtual-memory memory-management







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    Is there any way to force the kernel to always maintain at least some page cache for writeback caching purposes, even when faced with memory pressure?



    I have a rather special use case, where swapping to zswap is much more preferable than not having a large page cache. (I have set the relevant vm.dirty values to allow a lot of write caching)



    So what I would like, is set a minimum page cache size (say 10-30% of total RAM), and if memory usage rises, instead of flushing dirty pages, the kernel should start swapping (I am using zswap, so that would just mean compressing pages, but still keeping most of them in RAM)



    I have tried raising vm.swappiness to 100, and lowering vm.vfs_cache_pressure to 10, but this does not seem to have cut it.






    memory swap cache virtual-memory memory-management







    share|improve this question







    New contributor




    uLoop is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.





















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      up vote
      1
      down vote

      favorite











      Is there any way to force the kernel to always maintain at least some page cache for writeback caching purposes, even when faced with memory pressure?



      I have a rather special use case, where swapping to zswap is much more preferable than not having a large page cache. (I have set the relevant vm.dirty values to allow a lot of write caching)



      So what I would like, is set a minimum page cache size (say 10-30% of total RAM), and if memory usage rises, instead of flushing dirty pages, the kernel should start swapping (I am using zswap, so that would just mean compressing pages, but still keeping most of them in RAM)



      I have tried raising vm.swappiness to 100, and lowering vm.vfs_cache_pressure to 10, but this does not seem to have cut it.






      memory swap cache virtual-memory memory-management







      share|improve this question







      New contributor




      uLoop is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      Is there any way to force the kernel to always maintain at least some page cache for writeback caching purposes, even when faced with memory pressure?



      I have a rather special use case, where swapping to zswap is much more preferable than not having a large page cache. (I have set the relevant vm.dirty values to allow a lot of write caching)



      So what I would like, is set a minimum page cache size (say 10-30% of total RAM), and if memory usage rises, instead of flushing dirty pages, the kernel should start swapping (I am using zswap, so that would just mean compressing pages, but still keeping most of them in RAM)



      I have tried raising vm.swappiness to 100, and lowering vm.vfs_cache_pressure to 10, but this does not seem to have cut it.






      memory swap cache virtual-memory memory-management




      memory swap cache virtual-memory memory-management






      share|improve this question







      New contributor




      uLoop is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question







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