Designing Applications for High Performance - Part III

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Running Microsoft SQL Server 2008 Analysis Services on Windows Server 2008 vs. Windows Server 2003 and Memory Preallocation: Lessons Learned

Technical Notes — Wed, 16 Jul 2008 20:06:07 GMT

Author: Carl Rabeler Contributers: Eric Jacobsen, Thomas Kejser Technical Reviewers: Brad Daniels, Lindsey

re: Designing Applications for High Performance - Part III

John Davis — Wed, 20 Aug 2008 17:53:32 GMT

Rick, why does non-blocking i/o outperform IOCP on UDP sockets when sending/receiving small packets (ie 300 bytes) This includes using send/recv overlap depths of up to 128 combined with GetQueueCompletionStatusEx with an array of 128 completion notification entries.

Since you are using GQCSEx, it must be Vista or above. By “non-blocking i/o” I assume you mean receiving IO completion notification by calling WaitForSingleObject on the EventObject in the IOSB (although you might be scanning the status field in the IOSBs like SQL). Since depth is 128, WaitForMultiple probably isn’t used.

It is surprising that GQCS isn’t outperforming WaitForSingleObject because there is no IO completion APC and no dispatcher lock acquire per IO. That usually makes a significant difference with many cpus, but it should be at least equal on UP.

It is possible that setting the “don’t queue a phony completion if the IO completes in-line” option might help, but there is probably some other interaction going on. Is it possible to get an ETW trace (with CSWITCH+LOADER+PROC_THREAD+DISPATCHER+DPC and stacks)?

---rick

re: Designing Applications for High Performance - Part III

John Davis — Thu, 21 Aug 2008 00:57:45 GMT

How do I do an ETW trace, etc.?

There is information on ETW at http://www.microsoft.com/whdc/system/sysperf/perftools.mspx & http://blogs.msdn.com/pigscanfly/archive/tags/xperf/default.aspx

Also, there is a lot of built-in help:

xperf –help stackwalk

xperf –help symbols

Here is what I use for a quick look (must run as admin):

xperf -on CSWITCH+LOADER+PROC_THREAD+DPC+DISPATCHER -maxfile 100 -buffersize 512 -stackwalk CSWITCH+READYTHREAD

pause

xperf -d cswitch.bin

xperf -i cswitch.bin -symbols -a dumper >mytrace.txt

re: Designing Applications for High Performance - Part III

Don Burn — Sun, 06 Sep 2009 22:53:11 GMT

I am trying to use SetFileIoOverlappedRange and SetFileCompletionNotificationModes in a program to drive my device. But whatever I do I keep getting ERROR_ACCESS_DENIED on both calls. Unfortunately the documentation is a little lite, and I am at a loss.

re: Designing Applications for High Performance - Part III

winsrvperf — Thu, 10 Sep 2009 00:04:04 GMT

Are you sure it is ACCESS_DENIED and not INVALID_PARAMETER? It will return INVALID_PARAMETER if called on a file opened without the OVERLAPPED flag. The only way I can see it returning ACCESS_DENIED is if you really don't have read/write access to the file. Try SetFileShortName (see MSDN for usage). It exercises the same underlying code to get access to the file before branching to the function-specific code.