# Suboptimal use of compute Savings Plans for specialized instances Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/suboptimal-use-of-compute-savings-plans-for-specialized-instances Accelerated EC2 instance types such as `p5.48xlarge` and `p5en.48xlarge (often used for ML/AI workloads)` are eligible for Compute Savings Plans, but... By: David Gross Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) # Suboptimal Use of Compute Savings Plans for Specialized Instances The short version Accelerated EC2 instance types such as \`p5.48xlarge\` and \`p5en.48xlarge (often used for ML/AI workloads)\` are eligible for Compute Savings Plans, but the discount rates offered are modest compared to more common instance families. [David Gross](https://www.linkedin.com/in/davidgross/) Senior Staff, Cloud Planning Engineering @ Celonis AWS service [AWS EC2](https://www.pointfive.co/efficiency-hub/cloud-services/aws-ec2) Category [Compute](https://www.pointfive.co/efficiency-hub/service-category/compute) Reference CER-0108 Type Suboptimal Pricing Model ## Explanation Why the waste happens and who it affects. When organizations rely solely on CSPs, these lower priority instances are typically the last to benefit from the plan, especially if other instance types consume most of the discounted hours. As a result, p5 usage may fall through the cracks and be billed at full On-Demand rates despite an active CSP. This dynamic makes CSPs a potentially inefficient choice for workloads that heavily or predictably rely on these instance types. EC2 Instance Savings Plans provide better discount targeting for known usage patterns, and EC2 Instance Savings Plans for P5 and P5en are available in 3-year terms and, since June 2025, 1-year terms with up to 40% savings compared to On-Demand. AWS also reduced P5 and P5en On-Demand and Savings Plan prices in June 2025, so older CSP discount comparisons may be out of date. Additionally, Capacity Blocks provide reserved GPU capacity for fixed windows at reservation prices that AWS updates based on supply and demand, but they come with operational rigidity and inflexible scheduling constraints that limit their applicability. ## Billing model The pricing dimensions that drive this cost. AWS EC2 instances can be purchased via multiple pricing models: On-Demand, Compute Savings Plans (CSPs), EC2 Instance Savings Plans, Reserved Instances, and Capacity Blocks (for specific accelerated instance types). Compute Savings Plans apply dollar-based discounts based on discount percentage priority, with savings first applied to usage with the highest discount percentage. If multiple instances have the same discount percentage, the plan applies to usage with the lowest rate. This allocation methodology can result in accelerated instances like p5.48xlarge and p5en.48xlarge receiving lower priority if its discount percentages are less competitive than other instance types in the environment. For accelerated instances like \`p5.48xlarge\` and \`p5en.48xlarge\`, CSPs may offer relatively low discount rates, which makes them both less cost-effective and deprioritized in CSP allocation. This can lead to uncovered spend on these expensive instances unless the total CSP commitment is large enough to cover all usage. ## How to detect 8 checks to find it in your estate. - Review usage patterns of high-cost accelerated instances such as \`p5.48xlarge\` and \`p5en.48xlarge\` - Determine if these instances are being run consistently at high utilization levels - Assess how much of their usage is actually covered under existing Compute Savings Plans - Verify current CSP discount rates for various instances in your specific regions, as rates vary by region, term, and payment option - Evaluate whether other instance types with higher CSP discount rates are exhausting the plan allocation - Compare costs against dedicated EC2 Instance Savings Plans (available in 1-year and 3-year terms for P5 and P5en) for predictable workloads - Confirm whether an EC2 Instance Savings Plan would have better alignment with observed usage patterns - Identify potential overcommitment risks if CSPs were scaled up solely to include p-type instance usage ## How to fix 6 ways to remove the waste. - Consider using dedicated EC2 Instance Savings Plans instead of CSPs for predictable, high-utilization p5 workloads - Model CSP allocation on actual discount percentages in order to determine whether p-type instances are likely to be left uncovered - Compare total cost of ownership between CSPs and dedicated instance savings plans for your specific usage patterns - Evaluate potential fit for Capacity Blocks only if workloads are short-term, highly predictable, and operationally isolated - Ensure any long-term commitment aligns with actual usage patterns and instance mix - Review and update savings plan strategy as AWS introduces new instance-specific savings plan options ## Documentation Vendor references for pricing and configuration. - [Understanding how Savings Plans apply to your usage docs.aws.amazon.com](https://docs.aws.amazon.com/savingsplans/latest/userguide/sp-applying.html) - [Compute Savings Plans aws.amazon.com](https://aws.amazon.com/savingsplans/compute-pricing/) - [One Year EC2 Instance Savings Plans are now available for P5 and P5en instances aws.amazon.com](https://aws.amazon.com/about-aws/whats-new/2025/06/one-year-ec2-instance-savings-plans-p5-p5en-instances/) - [Pricing and usage model updates for Amazon EC2 instances accelerated by NVIDIA GPUs aws.amazon.com](https://aws.amazon.com/about-aws/whats-new/2025/06/pricing-usage-model-ec2-instances-nvidia-gpus/) - [Amazon EC2 Capacity Blocks for ML Pricing aws.amazon.com](https://aws.amazon.com/ec2/capacityblocks/pricing/) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - AWS EC2 CER-0324 ### [Excessive On-Demand Compute Spend Due to Low Savings Plan and Reserved Instance Coverage](https://www.pointfive.co/efficiency-hub/inefficiencies/excessive-on-demand-compute-spend-due-to-low-savings-plan-and-reserved-instance-coverage) AWS compute services charge the full published On-Demand rate when no commitment-based discount - such as a Savings Plan (SP) or Reserved Instance (RI) - is in effect. On-Demand pricing provides maximum flexibility, but it is also the most... Compute - AWS EC2 CER-0012 ### [Suboptimal Use of On-Demand Instances in Fault-Tolerant EC2 Workloads](https://www.pointfive.co/efficiency-hub/inefficiencies/suboptimal-use-of-on-demand-instances-in-fault-tolerant-ec2-workloads) Many EC2 workloads - such as development environments, test jobs, stateless services, and data processing pipelines-can tolerate interruptions and do not require the reliability of On-Demand pricing. Using On-Demand instances in these... Compute - AWS EC2 CER-0327 ### [Spot Instance Overreliance Without Effective Cost-Per-Performance Analysis](https://www.pointfive.co/efficiency-hub/inefficiencies/spot-instance-overreliance-without-cost-per-performance-analysis) Organizations frequently pursue aggressive Spot Instance adoption based on headline discount percentages - up to 90% off On-Demand pricing - without evaluating the effective cost per unit of work completed. While Spot pricing can deliver... Compute --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.