FAQ Is Linux kernel version important to read-page-cache?

FAQ Is Linux kernel version important to read-page-cache?

Detail

read-page-cache was introduced in Aerospike 4.3.1 to leverage the OS page cache. It can lead to lower latencies with certain workload types. With this in mind, how important is kernel version when using read-page-cache?

Answer

Kernel version is not critically important in terms of read-page-cache. The reason for this is that page cache improvements that may be found in later kernel versions focus on faster I/O between the device and the page cache. This would only become apparent when there is a cache miss and the data has to be brought back from disk into RAM, generating I/O. In the case of a cache hit the page already exists in RAM and so no I/O is necessary. read-page-cache is normally enabled for workloads where a high number of cache hits are expected and as such I/O performance is less of a critical factor. read-page-cache exists to reduce I/O.

Notes

When the primary index is on disk (All Flash), kernel version becomes very important. Unlike read-page-cache, index on disk does not use the page cache for caching, the page cache is used as a means to offload I/O to the kernel. For that reason, the latest kernel version is always preferred for All Flash configurations.

Aerospike has an article on buffering and caching here

Keywords

CACHE READ-PAGE-CACHE KERNEL VERSION INDEX-ON-DISK

Timestamp

3/19/2019

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