Re: How to investigate an unexpected port build time-taken relationship in an aarch64 context?

On Feb 28, 2024, at 18:46, Mark Millard <[email protected]> wrote:

> Example HW Context: Windows Development Kit 2023
> 8 cores: 4 cortex-A78C's and 4 cortex-X1C's
> Headless: serial console and ssh access, no x11 or the like installed.
> UFS use.
> 
> Note: cortex-A76's are missing 3 or so instruction set
> features compared to A78C/X1C parts. Use of
> -mcpu=cortex-a76 generated code is compatibile (and would allow
> the code to run on a cortex-a76 system, such as an RPi5 once
> supported).
> 
> I've been doing poudriere-devel bulk timing experiments based on:
> 
> A) PkgBase based system software (kernel and world) and
> general use of default code generation for ports and
> such.
> 
> B) A personal -mcpu=cortex-a76 based kernel, world, port builds
> (into packages via poudriere-devel).
> 
> C) Also use of an armv7 poudriere jail based on armv7 PkgBase
> and default armv7 code generation. This was used in both the
> (A) and (B) contexts. These also show what I'm curious about.
> 
> Using the armv7 poudriere jail context for illustration:
> 
> For (B) used via the armv7 context:
> 
> [05:40:24] [03] [04:55:38] Finished lang/rust | rust-1.76.0: Success
> . . .
> [05:45:58] [01] [05:01:12] Finished devel/llvm18@default | llvm18-18.1.0.r3: Success
> [05:46:00] [01] [00:00:00] Building devel/boost-libs | boost-libs-1.84.0
> [06:59:23] [01] [01:13:23] Finished devel/boost-libs | boost-libs-1.84.0: Success
> 
> For (A) used via the armv7 poudriere jail context:
> 
> [06:33:21] [01] [05:40:48] Finished lang/rust | rust-1.76.0: Success
> . . .
> [06:40:05] [05] [05:48:09] Finished devel/llvm18@default | llvm18-18.1.0.r3: Success
> [06:40:07] [01] [00:00:00] Building devel/boost-libs | boost-libs-1.84.0
> [06:57:48] [01] [00:17:41] Finished devel/boost-libs | boost-libs-1.84.0: Success
> 
> The curiosity is about the 01:13:23 vs. 00:17:41 boost-libs: The
> ratio is large and in the opposite direction to most time trends.
> 
> Notes: Almost all the time llvm18 and rust were building, both were
> building but little else did and the load average was 16+ from the
> llvm18/rust build activity. When boost-libs was building it was the
> only thing building and it looked to be single threaded when I
> was watching.

I should have been explicit that the 01:13:23 was mostly
"stage" phase (not "build" phase) and I was referring to
the "stage" phase as far as single  threaded is concerned.

> (A) and (B) without use of the armv7 context got similar results
> when I first noticed this but I'm going back and recording times
> for some variations. I do not have those to report other
> pairs of results yet.
> 
> (In the armv7 poudriere jail context reported:)
> (B) takes less time for llvm18 and rust than (A) does.
> (A) takes vastly less time for boost-libs than (B) does,
> approximately a factor of 4 for the time-ratio.
> 
> I'd be curious to get a clue what contributes to the boost-libs
> time ratio being so extreme once I have figures for other
> combinations of poudriere jail content vs. the system's content.

Turns out that for the aarch64 jail (PkgBase system and
default code generation), stage started about 10 min into
the boost-libs activity. Package started somewhat under 5
minutes later. End result:

[05:55:56] [03] [05:33:12] Finished lang/rust | rust-1.76.0: Success
 . .
[06:04:37] [01] [05:41:53] Finished devel/llvm18@default | llvm18-18.1.0.r3: Success
[06:04:39] [01] [00:00:00] Building devel/boost-libs | boost-libs-1.84.0
[06:20:50] [01] [00:16:11] Finished devel/boost-libs | boost-libs-1.84.0: Success

So, very similar to the armv7 jail result for a PkgBase
system context (aarch64 boot and aarch64/armv7 PkgBase
jail, default code generation).

It appears that the boost-libs "stage" phase is the context
for my question.

For the jail code generation being based on -mcpu=cortex-a76
code generation but the boot having been PkgBase based:

Stage started about 11.5 min into the boost-libs activity.
Package started around 48 minutes later. End result
(showing only boost-libs):

[01:07:01] [01] [01:06:31] Finished devel/boost-libs | boost-libs-1.84.0: Success

I'll note that bjam stays around 100% CPU in top during this
much longer "stage" phase. Definitely less than the 01:13:23
time. MWCHAN "-", STAT RJ, PRI 135 when I looked.

For the jail code generation and boot context both being based
on -mcpu=cortex-a76 code generation:

[05:16:38] [01] [00:49:22] Finished devel/boost-libs | boost-libs-1.83.0_1: Success

Also definitely less than the 01:13:23 time. (I'm showing here an
earlier test when it was boost-libs v1.83.)

A ZFS context (instead of UFS context) showed:

[04:37:47] [03] [04:03:16] Finished lang/rust | rust-1.76.0: Success
 . .
[04:43:47] [01] [04:09:16] Finished devel/llvm18@default | llvm18-18.1.0.r3: Success
[04:43:48] [01] [00:00:00] Building devel/boost-libs | boost-libs-1.84.0
[05:41:46] [01] [00:57:58] Finished devel/boost-libs | boost-libs-1.84.0: Success

===
Mark Millard
marklmi at yahoo.com