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Date:      Mon, 23 Jul 2018 00:11:19 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        Trev <freebsd-arm@sentry.org>, freebsd-arm@freebsd.org
Subject:   Re: RPI3 swap experiments
Message-ID:  <AB5EE2E4-B2FD-4CA9-A993-04C2A4BE10AE@yahoo.com>
In-Reply-To: <20180723063526.GA45726@www.zefox.net>
References:  <20180629155131.GA35717@www.zefox.net> <c6b8842a-fcc5-8e11-5a03-ba76eb3c5dea@sentry.org> <20180629233937.GC35717@www.zefox.net> <0f137e06-214a-3e8c-a216-f061ec04ac2c@sentry.org> <20180630005145.GA43801@www.zefox.net> <6f3406e2-71f3-d0c2-2b65-703e1a1d3c25@sentry.org> <8e92b2b7-da61-3efb-7231-9fac76b2c1d4@sentry.org> <ba33d8a7-a849-3893-8016-0765ebe1c51f@sentry.org> <2deaaec3-f78f-0b09-5ca7-27e14c6979f9@sentry.org> <bc8da02c-4465-9634-6fd0-0af4c63aa49d@sentry.org> <20180723063526.GA45726@www.zefox.net>

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On 2018-Jul-22, at 11:35 PM, bob prohaska <fbsd at www.zefox.net> wrote:

>> . . .
> There is some reason to think "newer" Sandisk Extreme devices differ, =
perhaps
> in a bad way, from older devices. The older device in my tests is =
model
> SDCZ80-064G and is simply labeled USB3.0. The newer, troublesome =
device
> is model SDCZ800-064G and is labeled Extreme Go USB 3.1. There are =
reports
> that the Extreme Go is slower, advising to buy the older devices if =
possible.
>=20
> The USB3.1 flash drive is back in test, with the results of a j4 =
buildworld
> under r336567 at
> http://www.zefox.net/~fbsd/rpi3/swaptests/r336567/
>=20
> The worst case results are still fairly dismal, close to a minute. All =
the
> swap was on microSD, so OOMA didn't strike and buildworld completed =
successfully.
> Near as I can tell no errors were reported on the console.


Rebuilds that do not rebuild the llvm materials (clang, lld, lldb, etc.) =
are not all that
comparable to ones that do. (This is visible in the time differences in =
the builds that
complete.) The llvm related build activity likely involves most of the =
potential
swapping, for example. Also: lots of I/O.

There can be two rebuilds of some of the llvm material. One stage with =
such is the
cross-compiler:
--- buildworld ---
make[1]: "/usr/src/Makefile.inc1" line 341: SYSTEM_COMPILER: Determined =
that CC=3Dcc matches the source tree.  Not bootstrapping a =
cross-compiler.
make[1]: "/usr/src/Makefile.inc1" line 346: SYSTEM_LINKER: Determined =
that LD=3Dld matches the source tree.  Not bootstrapping a cross-linker.
(it was not rebuilt in the example). The other involves the build of the =
system llvm materials for
use in the (potentially) installed system, such as the system's clang.

Taking an environment that worked for lack of llvm related rebuilds may =
not
well indicate the result for rebuilds that would try to rebuild the llvm =
related
materials.

It is something to consider in what builds are compared, how they are
compared, and what one infers from comparisons.

=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net <http://dsl-only.net/>; went
away in early 2018-Mar)




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