| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Josh Berkus <josh(at)agliodbs(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Aidan Van Dyk <aidan(at)highrise(dot)ca>, Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Latches with weak memory ordering (Re: max_wal_senders must die) |
| Date: | 2010-11-20 19:05:33 |
| Message-ID: | AANLkTim8v6EMbA7LtS7AxYTiMPNxhnxuXz3=XYSkD6MW@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Nov 19, 2010 at 5:59 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> But what about timings vs. random other stuff? Like in this case
>> there's a problem if the signal arrives before the memory update to
>> latch->is_set becomes visible. I don't know what we need to do to
>> guarantee that.
>
> I don't believe there's an issue there. A context swap into the kernel
> is certainly going to include msync. If you're afraid otherwise, you
> could put an msync before the kill() call, but I think it's a waste of
> effort.
So what DO we need to guard against here?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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