Joaquim P.
Power Member
AMD com + dinheiro para evolução eheheh. Que venham os ryzen v2
The Retpoline approach is said to only have up to a ~1.5% performance hit when patched... I hope this weekend to get around to trying these kernel and GCC patches on some of my systems for looking at the performance impact in our commonly benchmarked workloads. The Retpoline work is separate from the KPTI page table isolation work for addressing the Intel CPU Meltdown issue.
https://access.redhat.com/articles/3307751In order to provide more detail, Red Hat’s performance team has categorized the performance results for Red Hat Enterprise Linux 7, (with similar behavior on Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 5), on a wide variety of benchmarks based on performance impact:
- Measureable: 8-19% - Highly cached random memory, with buffered I/O, OLTP database workloads, and benchmarks with high kernel-to-user space transitions are impacted between 8-19%. Examples include OLTP Workloads (tpc), sysbench, pgbench, netperf (< 256 byte), and fio (random I/O to NvME).
- Modest: 3-7% - Database analytics, Decision Support System (DSS), and Java VMs are impacted less than the “Measurable” category. These applications may have significant sequential disk or network traffic, but kernel/device drivers are able to aggregate requests to moderate level of kernel-to-user transitions. Examples include SPECjbb2005, Queries/Hour and overall analytic timing (sec).
- Small: 2-5% - HPC (High Performance Computing) CPU-intensive workloads are affected the least with only 2-5% performance impact because jobs run mostly in user space and are scheduled using cpu-pinning or numa-control. Examples include Linpack NxN on x86 and SPECcpu2006.
- Minimal: Linux accelerator technologies that generally bypass the kernel in favor of user direct access are the least affected, with less than 2% overhead measured. Examples tested include DPDK (VsPERF at 64 byte) and OpenOnload (STAC-N). Userspace accesses to VDSO like get-time-of-day are not impacted. We expect similar minimal impact for other offloads.