From: Konrad Hinsen <konrad.hinsen@fastmail.net>
To: zimoun <zimon.toutoune@gmail.com>
To: Guix Devel <guix-devel@gnu.org>
To: Ricardo Wurmus <rekado@elephly.net>
Subject: Re: Investigating a reproducibility failure
Date: Thu, 03 Feb 2022 10:16:55 +0100 [thread overview]
Message-ID: <m17dacb988.fsf@fastmail.net> (raw)
In-Reply-To: <CAJ3okZ3p0L9_KLjsOS+C1Jk6N7SbujTE7ygtA=u7BXRgkVZs3A@mail.gmail.com>
Hi Ricardo and Simon,
Thanks for your insight! I didn't even know about lscpu. The output for
my laptop is shown below. I tried building on a virtual machine, and
that works fine.
> CPU detection is a bottomless can of worms.
That sounds very credible. But what can we do about this?
There is obviously a trade-off between reproducibility and performance
here. Can we support both, in a way that users can understand and manage?
The OpenBlas package in Guix is (or at least was, back then) written for
performance. Can I, as a user, ask for a reproducible version? That
could either be a generic version for any x86 architecture (preferably),
or one that always builds for a given sub-architecture and then fails at
runtime if the CPU doesn't match.
Next: can I, as a user of dependent code, ask for reproducible versions
of all my dependencies? In my case, I was packaging Python code that
calls OpenBlas via NumPy. Many people in that situation don't even know
what OpenBlas is. I did know, but wasn't aware of the build-time CPU
detection.
There is of course the issue that we can never be sure if a build will
be reproducible in the future. But we can at least take care of the
cases where the packager is aware of non-reproducibility issues, and
make them transparent and manageable.
Cheers,
Konrad
--8<---------------cut here---------------start------------->8---
$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 39 bits physical, 48 bits virtual
CPU(s): 8
On-line CPU(s) list: 0-7
Thread(s) per core: 2
Core(s) per socket: 4
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 140
Model name: 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz
Stepping: 1
CPU MHz: 1800.000
CPU max MHz: 4800,0000
CPU min MHz: 400,0000
BogoMIPS: 3609.60
Virtualization: VT-x
L1d cache: 192 KiB
L1i cache: 128 KiB
L2 cache: 5 MiB
L3 cache: 12 MiB
NUMA node0 CPU(s): 0-7
Vulnerability Itlb multihit: Not affected
Vulnerability L1tf: Not affected
Vulnerability Mds: Not affected
Vulnerability Meltdown: Not affected
Vulnerability Spec store bypass: Mitigation; Speculative Store Bypass disabled via p
rctl and seccomp
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers and __user poi
nter sanitization
Vulnerability Spectre v2: Mitigation; Enhanced IBRS, IBPB conditional, RSB fi
lling
Vulnerability Srbds: Not affected
Vulnerability Tsx async abort: Not affected
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pg
e mca cmov pat pse36 clflush dts acpi mmx fxsr sse
sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm cons
tant_tsc art arch_perfmon pebs bts rep_good nopl xt
opology nonstop_tsc cpuid aperfmperf tsc_known_freq
pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm
2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2
x2apic movbe popcnt tsc_deadline_timer aes xsave av
x f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault
epb cat_l2 invpcid_single cdp_l2 ssbd ibrs ibpb st
ibp ibrs_enhanced tpr_shadow vnmi flexpriority ept
vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2
erms invpcid rdt_a avx512f avx512dq rdseed adx sma
p avx512ifma clflushopt clwb intel_pt avx512cd sha_
ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves
split_lock_detect dtherm ida arat pln pts hwp hwp_
notify hwp_act_window hwp_epp hwp_pkg_req avx512vbm
i umip pku ospke avx512_vbmi2 gfni vaes vpclmulqdq
avx512_vnni avx512_bitalg tme avx512_vpopcntdq rdpi
d movdiri movdir64b fsrm avx512_vp2intersect md_cle
ar flush_l1d arch_capabilities
--8<---------------cut here---------------end--------------->8---
next prev parent reply other threads:[~2022-02-03 9:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-02 20:35 Investigating a reproducibility failure zimoun
2022-02-02 23:43 ` zimoun
2022-02-03 9:16 ` Konrad Hinsen [this message]
2022-02-03 11:41 ` Ricardo Wurmus
2022-02-03 17:05 ` Konrad Hinsen
2022-02-03 12:07 ` zimoun
2022-02-05 14:12 ` Ludovic Courtès
2022-02-15 14:10 ` Bengt Richter
2022-02-16 12:03 ` zimoun
2022-02-16 13:04 ` Konrad Hinsen
2022-02-17 11:21 ` zimoun
2022-02-17 16:55 ` Konrad Hinsen
-- strict thread matches above, loose matches on Subject: below --
2022-02-01 14:05 Konrad Hinsen
2022-02-01 14:30 ` Konrad Hinsen
2022-02-02 23:19 ` Ricardo Wurmus
2022-02-02 23:36 ` Ricardo Wurmus
2022-02-05 14:05 ` Ludovic Courtès
2022-02-08 5:57 ` Konrad Hinsen
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