Re: Very poor read performance, query independent

From: Claudio Freire <klaussfreire(at)gmail(dot)com>
To: Charles Nadeau <charles(dot)nadeau(at)gmail(dot)com>
Cc: Igor Neyman <ineyman(at)perceptron(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Very poor read performance, query independent
Date: 2017-07-18 17:13:58
Message-ID: CAGTBQpYQw9V4QdC_m-TW-61Ode_eBpWQuikCEA0q9cFqtc+LvA@mail.gmail.com
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On Tue, Jul 18, 2017 at 1:01 PM, Claudio Freire <klaussfreire(at)gmail(dot)com> wrote:
> On Tue, Jul 18, 2017 at 6:20 AM, Charles Nadeau
> <charles(dot)nadeau(at)gmail(dot)com> wrote:
>> Claudio,
>>
>> At one moment
>> during the query, there is a write storm to the swap drive (a bit like this
>> case:
>> https://www.postgresql.org/message-id/AANLkTi%3Diw4fC2RgTxhw0aGpyXANhOT%3DXBnjLU1_v6PdA%40mail.gmail.com).
>> I can hardly explain it as there is plenty of memory on this server.
>
> That sounds a lot like NUMA zone_reclaim issues:
>
> https://www.postgresql.org/message-id/500616CB.3070408@2ndQuadrant.com

I realize you have zone_reclaim_mode set to 0. Still, the symptoms are
eerily similar.

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