Re: Postgres, fsync, and OSs (specifically linux)

On 2018-05-22 08:57:18 -0700, Andres Freund wrote:
> Hi,
> 
> 
> On 2018-05-22 17:37:28 +0200, Dmitry Dolgov wrote:
> > Thanks for the patch. Out of curiosity I tried to play with it a bit.
> 
> Thanks.
> 
> 
> > `pgbench -i -s 100` actually hang on my machine, because the
> > copy process ended up with waiting after `pg_uds_send_with_fd`
> > had
> 
> Hm, that had worked at some point...
> 
> 
> >     errno == EWOULDBLOCK || errno == EAGAIN
> > 
> > as well as the checkpointer process.
> 
> What do you mean with that latest sentence?
> 
> 
> > Looks like with the default
> > configuration and `max_wal_size=1GB` it writes more than reads to a
> > socket, and a buffer eventually becomes full.
> 
> That's intended to then wake up the checkpointer immediately, so it can
> absorb the requests.  So something isn't right yet.

Doesn't hang here, but it's way too slow. Reason for that is that I've
wrongly resolved a merge conflict. Attached is a fixup patch - does that
address the issue for you?

Greetings,

Andres Freund