You may want to consider the different types of disk I/O sub-systems in modern operating systems. Most *nix systems have Raw I/O support, Direct I/O support, Concurrent I/O support, Modular I/O support, etc. For example, most databases use raw I/O. Performance of these applications is usually better when using raw I/O rather than using other I/O methods, because it avoids the additional work of memory copies, logging, and inode locks.

My comment about perl was directed at which I/O subsystem perl was using, not that perl would be treated differently by that I/O sub-system.

When writing *nix utilities ( like grep ), system programmers were encouraged to write "cache aware" programs. Whenever possible, work on the cached version directly, and avoid memory to memory move/copy. ( For clarification, I use "move/copy" because the operating system may perform a move rather than a copy, but this happens in the paging I/O sub-system, and has to do with paging performance. This is transparent to the application. )

All I was trying to point out, was that a 500MB file on a test machine may be cached, but may not be cached on a production machine, and that a pure perl solution may very well be a better solution on a production machine. But that is the decision of the OP

"Well done is better than well said." - Benjamin Franklin


In reply to Re^5: search array for closest lower and higher number from another array by flexvault
in thread search array for closest lower and higher number from another array by bigbot

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