From: "Beckius, Mikael via lttng-dev" <lttng-dev@lists.lttng.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"lttng-dev@lists.lttng.org" <lttng-dev@lists.lttng.org>
Subject: Re: [lttng-dev] lttng-consumerd crash on aarch64 due to x86 arch specific optimization
Date: Mon, 6 Feb 2023 15:21:49 +0000 [thread overview]
Message-ID: <PH0PR11MB4904BF8DDA04502FFB89E35892DA9@PH0PR11MB4904.namprd11.prod.outlook.com> (raw)
In-Reply-To: <ea3518a5-e539-1616-432c-b7fe7fcada2f@efficios.com>
Hello Mathieu!
Sorry for the late reply. I was away for a few days.
I will have a look at your updated approach and get back to you on your other replies if still relevant, but in short:
- With __ARM_FEATURE_UNALIGNED defined 32-bit arm appears to support 2 and 4 bytes unaligned access
- Regarding 8 bytes I found this wording:
"__ARM_FEATURE_UNALIGNED is defined if the target supports unaligned access in hardware, at least to the extent of being able
to load or store an integer word at any alignment with a single instruction. (There may be restrictions on load-multiple and
floating-point accesses.)" on https://developer.arm.com/documentation/101028/0012/5--Feature-test-macros
and I think all the crash reports were about 8 bytes unaligned access on arm 32-bit
- Performance seems to improve for both aligned and unaligned access compared to using memcpy but your are right that a test needs to be carefully constructed
- 64-bit arm appears to support 2, 4 and 8 bytes unaligned access
Micke
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next prev parent reply other threads:[~2023-02-06 16:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-30 6:50 [lttng-dev] lttng-consumerd crash on aarch64 due to x86 arch specific optimization Beckius, Mikael via lttng-dev
2023-01-31 16:08 ` Mathieu Desnoyers via lttng-dev
2023-01-31 16:18 ` Mathieu Desnoyers via lttng-dev
2023-01-31 16:32 ` Mathieu Desnoyers via lttng-dev
2023-02-02 16:26 ` Mathieu Desnoyers via lttng-dev
2023-02-06 15:21 ` Beckius, Mikael via lttng-dev [this message]
2023-02-06 16:15 ` Beckius, Mikael via lttng-dev
2023-02-06 16:39 ` Mathieu Desnoyers via lttng-dev
[not found] <CAF2baFfZ+sxAGfxGY_or7=JJMxDngZTtfrzruUC5=RnZFD4tvA@mail.gmail.com>
[not found] ` <954909194.21985.1511551181212.JavaMail.zimbra@efficios.com>
[not found] ` <CAF2baFecVMCenooHSMcNChMEkevz1taF0VWUxWAyxbUq8kVXSg@mail.gmail.com>
2023-01-25 12:25 ` Mathieu Desnoyers via lttng-dev
2023-01-26 19:32 ` Anders Wallin via lttng-dev
2023-01-26 19:47 ` Mathieu Desnoyers via lttng-dev
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