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Hi, On Wed, 28 Jul 1999 16:12:59 -0700 (PDT), Gerald Aigner <aigner@stanford.edu> said: > I just profiled the 2.3.11 kernel and around 37% of the time was spend in > file_read_actor. By looking at the function I discovered that this > function is responsible for copying data from the kernel to the user > space. > Here the basic performance of this function: > data transfered: 1.8 GB > total execution time of the function: 23 seconds > --------------------------------------------------- > throughput per second: 78 MB/sec > This means that the Linux memory copy function used for copying > disk data achieves a memory bandwidth of approximately 156 MB/sec > on a system with a 66 MHz system bus. Remember that you are doing disk IO here too so there is also 78MB/sec of bus traffic going between the scsi controller and main memory. That's also going to reduce the available bandwidth. Try doing a copy purely out of cache to see what the real memory bandwidth available via the filesystem is. --Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||
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