Issue 11
© Solarflare Communications 2014
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Solarflare Server Adapter
User Guide
TCP/IP Options
On Windows Server 2008 R2 and later platforms, TCP timestamps, window scaling and selective
acknowledgments are enabled by default and include receive window tuning and congestion control
algorithms that automatically adapt to 10 gigabit connections.
Server Power Saving Mode
Modern processors utilize design features that enable a CPU core to drop into low power states
when instructed by the operating system that the CPU core is idle. When the OS schedules work on
the idle CPU core (or when other CPU cores or devices need to access data currently in the idle CPU
core’s data cache) the CPU core is signaled to return to the fully on power state. These changes in
CPU core power states create additional network latency and jitter. Solarflare recommend to
achieve the lowest latency and lowest jitter that the "C1E power state" or "CPU power saving mode"
is disabled within the system BIOS.
In general the user should examine the system BIOS settings and identify settings that favor
performance over power saving. In particular look for settings to disable:
• C states / Processor sleep/idle states
• C1E
• Any deeper C states (C3 through to C6)
• P states / Processor throttling
• Ultra Low Power State
• PCIe Active State Power Management
• ASPM
• Processor Turbo mode
• Unnecessary SMM/SMI features