| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, John Naylor <johncnaylorls(at)gmail(dot)com> |
| Subject: | Re: suspicious valgrind reports about radixtree/tidstore on arm64 |
| Date: | 2024-06-19 23:33:21 |
| Message-ID: | 238963.1718840001@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
I wrote:
> I hypothesize that the reason we're not seeing equivalent failures
> on x86_64 is one of
> 1. x86_64 valgrind is stupider than aarch64, and fails to track that
> the contents of the SIMD registers are only partially defined.
> 2. x86_64 valgrind is smarter than aarch64, and is able to see
> that the "mask off invalid entries" step removes all the
> potentially-uninitialized bits.
Side note: it struck me that this could also be a valgrind version
skew issue. But the machine I'm seeing the failure on is running
valgrind-3.22.0-1.fc38.aarch64, which is the same upstream version
as valgrind-3.22.0-2.el8.x86_64, where I don't see it. So apparently
not. (There is a 3.23.0 out recently, but its release notes don't
mention anything that seems related.)
regards, tom lane
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