an ASP.NET performance bottleneck mystery

Question

A classic ASP.NET app - AppSrv + MS SQL DB. Both servers are heavy-lifters 8 cores, 20 GB of RAM. When load testing, the throughput goes somewhere to 400 VirtualUsers (according

Answer 1

We recently tuned our web application using the following IIS performance settings guide which proved very succesfull.

There were two server specific settings we changed;

Working Set Memory Usage - Servers running Windows Server™ 2003 are configured by default to give preference to the file system cache over the working set when allocating memory. Microsoft does this because Windows benefits from having a large file system cache. Being that IIS rides on top of the Windows operating system, it also benefits from having a large file system cache. If your server is a dedicated IIS Server, though, you might see better performance if you shift priority to the working set instead. The reason behind this is if preference is given to the file system cache, the pageable code is often written to virtual memory. The next time this information is needed, something else must be paged to virtual memory and the previously paged information must be read into physical memory before it can be used. This results in very slow processing.

Network Throughput - By default, servers running Windows Server 2003 are configured to give preference to the file system cache over the working sets of processes when allocating memory (through the server property Maximize data throughput for file sharing). Although IIS 6.0–based servers benefit from a large file system cache, giving the file system cache preference often causes the IIS 6.0 pageable code to be written to disk, which results in lengthy processing delays. To avoid these processing delays, set server properties to maximize data throughput for network applications.

The following services are not required on a dedicated Web server:

• Alerter
• ClipBook
• Computer Browser
• DHCP Client
• DHCP Server
• Fax Service
• File Replication
• Infrared Monitor
• Internet Connection Sharing
• Messenger
• NetMeeting Remote Desktop Sharing
• Network DDE
• Network DDE DSDM
• NWLink NetBIOS
• NWLink IPX/SPX
• Print Spooler
• TCP/IP NetBIOS Helper Service
• Telephony
• Telnet
• Uninterruptible Power Supply