[RESOLVED] Multiple thread question

[2kaud]

If you the time (and same curiosity as me), I'd be interested in an HD Tach screenshot.

Or you could run my I/O profiling code: http://forums.codeguru.com/showthrea...64#post1801264 (code attached at end of thread). You'll need to run the code posted in the thread first to create the files that profiling code works on.

gg

using stdio_read(), the i/o profiling code gives

Reading large file...please wait
Reading file chunks...please wait
Big file size   = 2147483647
Chunk file size = 10485760
# Chunks        = 205
Chunk Total     = 2149580800

Test                  = stdio_read
Buffer size           = 4 K
Time to read big file = 433809 ms
Time to read chunks   = 453293 ms
Big throughput        = 4.9503 MB/s
Chunk throughput      = 4.74214 MB/s
Throughput %Diff      = -4.29517 %

Test                  = stdio_read
Buffer size           = 32 K
Time to read big file = 230442 ms
Time to read chunks   = 261077 ms
Big throughput        = 9.31898 MB/s
Chunk throughput      = 8.23351 MB/s
Throughput %Diff      = -12.3682 %

Test                  = stdio_read
Buffer size           = 64 K
Time to read big file = 229467 ms
Time to read chunks   = 258999 ms
Big throughput        = 9.35857 MB/s
Chunk throughput      = 8.29957 MB/s
Throughput %Diff      = -11.9945 %

Test                  = stdio_read
Buffer size           = 128 K
Time to read big file = 234273 ms
Time to read chunks   = 262008 ms
Big throughput        = 9.16659 MB/s
Chunk throughput      = 8.20426 MB/s
Throughput %Diff      = -11.0798 %

Test                  = stdio_read
Buffer size           = 1024 K
Time to read big file = 228264 ms
Time to read chunks   = 257756 ms
Big throughput        = 9.40789 MB/s
Chunk throughput      = 8.3396 MB/s
Throughput %Diff      = -12.0389 %

Test                  = stdio_read
Buffer size           = 4096 K
Time to read big file = 229798 ms
Time to read chunks   = 257806 ms
Big throughput        = 9.34509 MB/s
Chunk throughput      = 8.33798 MB/s
Throughput %Diff      = -11.3907 %

Using win32_read() gives GetOverlappedResult failed error 38 (MessageId: ERROR_HANDLE_EOF //// MessageText://// Reached the end of the file.) on reading file chunks.