Runtime Environment Variables

The interface to the mp-umap service configuration is controlled by the following environment variables. Note: these environment variables only control mp-umap service’s configuration and does not effect applications using mpumapclient library. Also, client applications do not control and cannot modify service application’s configuration.

UMAP_PAGESIZE=$((2*4096)) your_program_that_uses_umap

The following environment varialbles may be set:

  • UMAP_PAGE_FILLERS This is the number of worker threads that will perform read operations from the backing store (including read-ahead) for a specific mp-umap region.

    Default: std::thread::hardware_concurrency()

  • UMAP_PAGE_EVICTORS This is the number of worker threads that will perform evictions of pages. Eviction includes writing to the backing store if the page is dirty and telling the operating system that the page is no longer needed.

    Default: std::thread::hardware_concurrency()

  • UMAP_EVICT_HIGH_WATER_THRESHOLD This is an integer percentage of present pages in the MP-Umap Buffer that informs the Eviction workers that it is time to start evicting pages.

    Default: 90

  • UMAP_EVICT_LOW_WATER_THRESHOLD This is an integer percentage of present pages in the MP-Umap Buffer that informs the Eviction workers when to stop evicting.

    Default: 70

  • UMAP_PAGESIZE This is the size of the MP-Umap pages. This must be a multiple of the system page size.

    Default: System Page Size

  • UMAP_BUFSIZE This is the total number of MP-Umap pages that may be present within the MP-Umap Buffer.

    Default: (90% of free memory)

  • UMAP_BUFADAPT_FREQ This sets the frequency with which the system memory pressure is evaluated for memory pressure. MP-Umap Buffer is adapted depending upon the memory pressure experienced by the system. This parameter is over-ridden when UMAP_BUFSIZE is set.

    Default: (3 seconds)