I tested a 20 GiB file under the host OS

Okay. Let's do a little math:

  1. grep: 21474836480 / 407 * 8 = 422109800 == 422Mbits/s.

    That is very fast. Way faster than my brand new disk and SSD; and equals the performance of the PCIe ssds on of my clients recently fitted to their servers.

    Very fast, but believable.

  2. mce_grep: 21474836480 / 137 * 8 = 1254005048 == 1.2Gbits/s.

    That is faster than any single device or interface that I have heard of.

  3. egrep.pl:21474836480 / 26.477 * 8 = 6495961426 == 6.5Gbits/s.

    That's getting up there with the bandwidth of the PCI Express 3.1 specifications (8GT/s); but as yet there are no devices available that support that!

  4. mce_loop_script: 21474836480 / 25.650 * 8 = 6697804750 == 6.7Gbits/s.

    That would give the Intel QuickPath Interconnect processor internal bus a run for its money on some of the low-powered, low clock-speed processors.

Sorry, but unless you have this file distributed across multiple spindles attached via multiple 16-lane PCIe cards; or maybe you're using a system that has 32GB of ram and you're pre-caching the file there as you were earlier; those numbers just don't add up.

especially when you (being at the Pope level) seem to disprove of MCE.

I don't disapprove of MCE.

I can see that for tasks where the IO is a small part of the overall processing time, -- example: fuzzy searching for many substrings against huge DNA sequences -- MCE provides a much needed solution for distributing the processing against a common dataset that threads (because of the slowness and gratuitous memory usage of threads::shared) simply doesn't have a good solution to.

For those types of processing, MCE is a breath of fresh air, and I applaud you for it.

But the numbers you are posting for this single file, single pass, simple search application seem to defy the laws of Physics.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". I'm with torvalds on this
In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked

In reply to Re^8: Threads From Hell #2: How To Parse A Very Huge File by BrowserUk
in thread Threads From Hell #2: How To Search A Very Huge File [SOLVED] by karlgoethebier

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