Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1uoQJj-003g0T-7C for pgsql-performance@arkaria.postgresql.org; Tue, 19 Aug 2025 17:40:16 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1uoQJi-00Fg8m-Ht for pgsql-performance@arkaria.postgresql.org; Tue, 19 Aug 2025 17:40:15 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1uoQJi-00Fg8e-7q for pgsql-performance@lists.postgresql.org; Tue, 19 Aug 2025 17:40:14 +0000 Received: from mail1.dalibo.net ([51.159.93.128] helo=mail.dalibo.com) by magus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uoQJg-000ktI-0j for pgsql-performance@lists.postgresql.org; Tue, 19 Aug 2025 17:40:14 +0000 Received: from [192.168.0.7] (5-49-10-71.hfc.dyn.abo.bbox.fr [5.49.10.71]) by mail.dalibo.com (Postfix) with ESMTPSA id 7AA97275DD; Tue, 19 Aug 2025 19:40:10 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dalibo.com; s=a; t=1755625210; bh=FzC+kbYhnmXZLKUItiEdapMMSS0UopEaw49cC2Geilk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pHS05PhDC24vhOuXaQNMJjp6JIqosJMfsVlNrDjvDHBlXHwLG/eQTcv+dRqZ6lIsX HRP1WxwQpyTyt61/89ex1d8XOs6VLluiv76H0dBRgC0iy0EgT8gInOPkwET+H6LfoK SYRlM4m6fj8J1FohYPznqUKZtDwdKucOeDT1X9ao= Message-ID: <98eb084c-457d-4638-8f1f-d14f9eb2a634@dalibo.com> Date: Tue, 19 Aug 2025 19:40:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Safe vm.overcommit_ratio for Large Multi-Instance PostgreSQL Fleet To: Frits Hoogland Cc: Joe Conway , Priya V , pgsql-performance@lists.postgresql.org References: <6e36e010-c93c-4d9b-a7ed-db6da1416716@dalibo.com> <08FF1C8D-DDA7-400C-9AC7-71A92AC925E7@gmail.com> From: =?UTF-8?Q?Fr=C3=A9d=C3=A9ric_Yhuel?= Content-Language: fr, en-US Autocrypt: addr=frederic.yhuel@dalibo.com; keydata= xjMEXn3bgxYJKwYBBAHaRw8BAQdA6tX5FT/n5ztMWIoBdl6k5avvu65fv6ryfVzIx/aH3V3N JEYuIFlodWVsIDxmcmVkZXJpYy55aHVlbEBkYWxpYm8uY29tPsKWBBMWCAA+FiEEi7OTyf6H ePS+C6n11XGWhN8zGNUFAmZDVJ8CGwMFCQtfi90FCwkIBwIGFQoJCAsCBBYCAwECHgECF4AA CgkQ1XGWhN8zGNV65gEA6o+UrebFjn2CIAOYwP3CiiJugiM5TMH9yJyehQua5ZoA/2ChxiVn 8OUaAw/ErxJmQi1mSN0tNZBL/KhkUPBDUDQNzjgEXn3bgxIKKwYBBAGXVQEFAQEHQCuh5cLQ AtEBXHa2Fmtp0kduBu7msM7qO/gaEcdjFUdiAwEIB8J+BBgWCAAmAhsMFiEEi7OTyf6HePS+ C6n11XGWhN8zGNUFAmZDVJ8FCQtfi90ACgkQ1XGWhN8zGNWOOAEArSqePBqfd4Kx4ulACaWO 6fM+XSDfUlBAQXx9rU6DR4MBALwozl9g91tRysim6lKxggvBfp/PvbpTZNrxYLWB2fYP In-Reply-To: <08FF1C8D-DDA7-400C-9AC7-71A92AC925E7@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On 8/19/25 17:37, Frits Hoogland wrote: > The specific issue I see in certain cases leading to unreasonable swap usage is Linux workingset detection kicking in Do you have a way to highlight that precisely? I mean, can you prove that it is Linux workingset detection that is causing swapping? I've also encountered surprising cases where the swap fills up despite there being plenty of available memory (lots of page cache). However these cases were not associated with slowdowns or other problems. I only became aware of them because a client was anxious about her swap usage.