Showing posts from January, 2018

PostgreSQL Performance Meltdown?

On the 30th of December 2017, Kernel page-table isolation (PTI) patch had been merged with the mainline. Its main goal was to mitigate the Meltdown bug. This patch has also been backpatched into the stable releases by RedHat, Debian, CentOS, Ubuntu and other Linux vendors. Therefore, the nearest security upgrade of the servers running on such stable releases will get PTI feature.
Unfortunately, this bugfix comes with the performance penalty. Andres Freund provided figures, showing that performance might drop by 7-23% on TPC-H alike workloads.
Meltdown vulnerability “allows a rogue process to read any kernel memory, even when it is not authorized to do so”. PTI is designed to close this flaw, i.e. restrict memory access to the unauthorized areas. Of course, this comes at a price and it’d be good to find out what performance impact it will have after Linux kernel upgrade. As PTI affects memory-based operations, one way to achieve this is to use database that fits into the RAM of the …