From: Adrian Bunk <bunk@stusta.de>
To: "André Draszik" <git@andred.net>
Cc: openembedded-core@lists.openembedded.org
Subject: Re: [PATCH v2] bitbake.conf: omit XZ threads and RAM from sstate signatures
Date: Mon, 24 Feb 2020 15:40:22 +0200 [thread overview]
Message-ID: <20200224134022.GB27036@localhost> (raw)
In-Reply-To: <20200224125955.26771-1-git@andred.net>
On Mon, Feb 24, 2020 at 12:59:55PM +0000, André Draszik wrote:
> The number of threads used, and the amount of memory allowed
> to be used, should not affect sstate signatures, as they
> don't affect the result.
Unfortunately they can affect the result.
> Otherwise, it becomes impossible to re-use sstate from
> automated builders on developer's machines (as the former
> might execute bitbake with certain constraints different
> compared to developer's machines).
>...
> -XZ_DEFAULTS ?= "--memlimit=50% --threads=${@oe.utils.cpu_count()}"
>...
Threaded compression can result in slightly worse compression
than single-threaded compression.
With memlimit the problem is actually the opposite way,
and worse than what you were trying to fix:
When a developer hits memlimit during compression, the documented
behavour of xz is to scale down the compression level.
I assume 50% wrongly gives the same sstate signature no matter how
much RAM is installed on the local machine?
cu
Adrian
next prev parent reply other threads:[~2020-02-24 13:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-24 12:59 [PATCH v2] bitbake.conf: omit XZ threads and RAM from sstate signatures André Draszik
2020-02-24 13:40 ` Adrian Bunk [this message]
2020-02-24 14:21 ` André Draszik
2020-02-24 14:31 ` Adrian Bunk
2020-02-24 14:58 ` André Draszik
2020-02-24 15:10 ` Adrian Bunk
2020-02-25 11:16 ` reproducible builds involving xz (was: Re: [PATCH v2] bitbake.conf: omit XZ threads and RAM from sstate signatures) André Draszik
2020-02-25 11:23 ` Richard Purdie
2020-02-24 16:44 ` [PATCH v2] bitbake.conf: omit XZ threads and RAM from sstate signatures Richard Purdie
2020-02-24 17:12 ` Adrian Bunk
2020-02-24 17:14 ` André Draszik
2020-02-24 17:32 ` Richard Purdie
2020-02-24 22:00 ` Adrian Bunk
2020-02-25 9:16 ` André Draszik
2020-02-25 9:54 ` Adrian Bunk
2020-02-26 15:26 ` xz threads / memlimit behaviour (was: Re: [PATCH v2] bitbake.conf: omit XZ threads and RAM from sstate signatures) André Draszik
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