Re: pread() and pwrite()

Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

To: jesper.pedersen@redhat.com, Tom Lane <tgl@sss.pgh.pa.us>

Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Magnus Hagander <magnus@hagander.net>, Oskari Saarenmaa <os@ohmu.fi>, Pg Hackers <pgsql-hackers@postgresql.org>, Tobias Oberstein <tobias.oberstein@gmail.com>

Date: 2018-11-07T15:27:23Z

Lists: pgsql-hackers

On 11/7/18 10:05 AM, Jesper Pedersen wrote:
> Hi Tom,
>
> On 11/7/18 9:30 AM, Tom Lane wrote:
>> I'm confused by this.  Surely the pwrite-based code is writing 
>> exactly the
>> same data as before.  Do we have to conclude that valgrind is 
>> complaining
>> about passing uninitialized data to pwrite() when it did not complain
>> about exactly the same thing for write()?
>>
>> [ looks ... ]  No, what we have to conclude is that the write-related
>> suppressions in src/tools/valgrind.supp need to be replaced or augmented
>> with pwrite-related ones.
>>
>
> The attached patch fixes this for me.
>
> Unfortunately pwrite* doesn't work for the pwrite64(buf) line.
>
>


Works for me. If there's no objection I will commit this.


cheers


andrew


-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

Use pg_pread() and pg_pwrite() for data files and WAL.
- c24dcd0cfd94 12.0 landed
Provide pg_pread() and pg_pwrite() for random I/O.
- 3fd2a7932ef0 12.0 landed
Convert some long lists in configure.in to one-line-per-entry style.
- bfa6c5a0c974 12.0 landed