On Fri, 06 Mar 2020 13:52:06 +0000, Jan Panteltje wrote:

> 9 minutes, 540 seconds, makes little difference, Pi4_speed / P2_speed =
> 540 / 17 = more than 31 times faster.
>
>
Does the Pi 4 show the same difference in speed between successive
identical compiler runs without a reboot or disk switch in between?

On this T440  I see the same speed-up for subsequent compilations
compared with the first following a reboot or switch from other workloads.
Its not specific to C either: Open Java 1.8 does exactly the same, though
I haven't yet attempted to measure the speed difference for ant-
controlled Java compoilation.

The R61i it replaced, which, BTW has 3GB of RAM and a Core Duo chip
clocked at 1.6 GHz, used to show the same speed difference.

I bought the T440 when the R61i disk failed and I discovered that its
disk interfacing electronics could not handle a disk bigger than 250 GB,
and at the time all disks under 320 GB were no longer available. I
subsequently revived the machine by fitting a 128GB Sandisk SSD and I've
just timed that using the ecaxt same workload.

The 1 st compilation after booting it took 2.540 seconds and the second
one took 2.217 secs , so the cache has a tiny effect, but thats largely
masked by the much greater speed of the SSD.

The T440 has a 500 GB Toshiba HDD installed, which threw its first hard
error last weekend (at around 21,000 hours and no problems since) so I
bought a WD Black drive to replace it: I'll be very interested to see
what effect its large (32MB) cache has on overall system performance when
the Tosh finally dies and gets replaced.


--
Martin    | martin at
Gregorie  | gregorie dot org

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