From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Remove or weaken hints about "effective resolution of sleep delays is 10 ms"? |
Date: | 2016-02-16 12:39:51 |
Message-ID: | CA+TgmoaRPREkynkF5gnm0T_6qpkv02KB5XV8ESBOu=py8FprMw@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Feb 16, 2016 at 3:50 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2016-02-16 09:13:09 +0100, Andres Freund wrote:
>> What we do we think the resolution is on modern
>> >systems? I would not have guessed that to be inaccurate.
>>
>> Depends in a lot of factors. The biggest being how busy you're system
>> is. On an mostly idle system (i.e. workout so CPUs being
>> overcommitted) you can get resolutions considerably below one
>> millisecond. HPET can get you very low latencies, making OS scheduling
>> latencies the dominant factor, but one that can be tuned.
>
> To back up my claim on this, read man 7 time
> (e.g. http://linux.die.net/man/7/time), especially "The software clock,
> HZ, and jiffies" and "High-resolution timers". To quote the most salient
> point:
Interesting, thanks.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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