| Lists: | pgsql-hackers |
|---|
| From: | Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru> |
|---|---|
| To: | pgsql-hackers(at)lists(dot)postgresql(dot)org, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Declare PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY for aarch64 |
| Date: | 2022-03-16 12:32:35 |
| Message-ID: | [email protected] |
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| Lists: | pgsql-hackers |
Good day, hackers.
Architecture Reference Manual for ARMv8 B2.2.1 [1] states:
For explicit memory effects generated from an Exception level the
following rules apply:
- A read that is generated by a load instruction that loads a single
general-purpose register and is aligned to the size of the read in the
instruction is single-copy atomic.
- A write that is generated by a store instruction that stores a single
general-purpose register and is aligned to the size of the write in the
instruction is single-copy atomic.
So I believe it is safe to define PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY
for aarch64
[1] https://documentation-service.arm.com/static/61fbe8f4fa8173727a1b734e
https://developer.arm.com/documentation/ddi0487/latest
-------
regards
Yura Sokolov
Postgres Professional
y(dot)sokolov(at)postgrespro(dot)ru
funny(dot)falcon(at)gmail(dot)com
| Attachment | Content-Type | Size |
|---|---|---|
| v0-0001-Declare-aarch64-has-single-copy-atomicity-for-8-b.patch | text/x-patch | 1.5 KB |
| From: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
|---|---|
| To: | Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: Declare PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY for aarch64 |
| Date: | 2022-03-18 00:50:49 |
| Message-ID: | CA+hUKGK=eeHw42wXak-zEYhWdcbwtedTAGt4rR-0i=AU+YUisg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Mar 17, 2022 at 1:32 AM Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru> wrote:
> So I believe it is safe to define PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY
> for aarch64
Agreed, and pushed. There was another thread that stalled, so I added
a reference and a reviewer from that to your commit message.
This should probably also be set for RISCV64.