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2017 iMac 5K: Grep (Search)
MPG recommends 64GB OWC memory (big savings!) in: 27" Retina 5K Display, 4.2 GHz Intel Core i7 (Skylake), 1TB Flash, 8GB memory, AMD Radeon Pro 580 Graphics Card (8GB).
MPG tested a fully-loaded 2017 MacBook Pro with 1TB SSD.
This test uses grep at the command line in Terminal. Grep is single-threaded, using only one CPU core. Its performance is thus sensitive to how fast the CPU core is, provided that the SSD can read data fast enough and/or if the data is cached.
This test is a good proxy for any activity that has to scan large numbers of text files.
All machines used the Apple internal 1TB SSD.
Test repeated 5 times; the best time was used for each machine. There was low variability.
alias grepHTML='find . -name '\''*.html'\'' | xargs grep '
Uncached test: sudo purge; time grepHTML hello123
Cached test: time grepHTML hello123
The test was repeated several times, with consistent results. It is a good example of how performance expectatations/assumptions are no substitute for actual measurement. And that high peak transfer speed does not mean that small I/O performance will be equally good.
Be careful what you wish for, because small I/O speed is usually much more important than the peak speed for very large transfers.
The 2017 iMac 5K is slower than the 2015 iMac 5K is actually slower than the 2015 MacBook Pro in this test, just as the 2017 MacBook Pro is slower than the 2015 MacBook Pro. Seems like Apple has made a change to SSDs that is not for the better.
The 2017 iMac 5K SSD is incredibly fast for huge I/O transfer sizes—but as measured by DiskTester in SSD Speed vs Transfer Size, its small I/O speed is inferior to that of the 2015 iMac 5K, or even the 2013 Mac Pro, as confirmed by this test! Apparently Apple has degraded the most important aspect of SSD performance to achieve higher peak speeds—disappointing to not have at least maintained the smaller I/O performance. Another reason that Adobe needs to get on the ball for Photoshop and Lightroom I/O performance.
The fastest performer here is the 2015 iMac 5K! The worst performer is the 2017 iMac 5K!