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ba2a3c2302
Introduces a new view pg_buffercache_numa, showing NUMA memory nodes for individual buffers. For each buffer the view returns an entry for each memory page, with the associated NUMA node. The database blocks and OS memory pages may have different size - the default block size is 8KB, while the memory page is 4K (on x86). But other combinations are possible, depending on configure parameters, platform, etc. This means buffers may overlap with multiple memory pages, each associated with a different NUMA node. To determine the NUMA node for a buffer, we first need to touch the memory pages using pg_numa_touch_mem_if_required, otherwise we might get status -2 (ENOENT = The page is not present), indicating the page is either unmapped or unallocated. The view may be relatively expensive, especially when accessed for the first time in a backend, as it touches all memory pages to get reliable information about the NUMA node. This may also force allocation of the shared memory. Author: Jakub Wartak <jakub.wartak@enterprisedb.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Reviewed-by: Tomas Vondra <tomas@vondra.me> Discussion: https://postgr.es/m/CAKZiRmxh6KWo0aqRqvmcoaX2jUxZYb4kGp3N%3Dq1w%2BDiH-696Xw%40mail.gmail.com
The PostgreSQL contrib tree
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