From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <dietmar@proxmox.com>
Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68])
 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
 key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256)
 (No client certificate requested)
 by lists.proxmox.com (Postfix) with ESMTPS id D7AF86B93E;
 Wed, 17 Mar 2021 17:03:57 +0100 (CET)
Received: from firstgate.proxmox.com (localhost [127.0.0.1])
 by firstgate.proxmox.com (Proxmox) with ESMTP id C3F8D88B9;
 Wed, 17 Mar 2021 17:03:27 +0100 (CET)
Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com
 [212.186.127.180])
 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
 key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256)
 (No client certificate requested)
 by firstgate.proxmox.com (Proxmox) with ESMTPS id B7FAD88A9;
 Wed, 17 Mar 2021 17:03:26 +0100 (CET)
Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1])
 by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 870D642774;
 Wed, 17 Mar 2021 17:03:26 +0100 (CET)
Date: Wed, 17 Mar 2021 17:03:02 +0100 (CET)
From: Dietmar Maurer <dietmar@proxmox.com>
To: Proxmox Backup Server development discussion <pbs-devel@lists.proxmox.com>, 
 Thomas Lamprecht <t.lamprecht@proxmox.com>,
 Stefan Reiter <s.reiter@proxmox.com>,
 Proxmox VE development discussion <pve-devel@lists.proxmox.com>
Message-ID: <1616415645.211.1615996982921@webmail.proxmox.com>
In-Reply-To: <9177e016-7e42-cee7-f948-887af087311c@proxmox.com>
References: <20210303095612.7475-1-s.reiter@proxmox.com>
 <20210303095612.7475-6-s.reiter@proxmox.com>
 <f3df01a9-71a6-9b20-dafa-3cdda78f2e72@proxmox.com>
 <570fbf9f-988c-c3a7-1475-ff0406ca590e@proxmox.com>
 <9177e016-7e42-cee7-f948-887af087311c@proxmox.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
X-Priority: 3
Importance: Normal
X-Mailer: Open-Xchange Mailer v7.10.4-Rev20
X-Originating-Client: open-xchange-appsuite
X-SPAM-LEVEL: Spam detection results:  0
 AWL 0.110 Adjusted score from AWL reputation of From: address
 KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment
 RCVD_IN_DNSWL_MED        -2.3 Sender listed at https://www.dnswl.org/,
 medium trust
 SPF_HELO_NONE           0.001 SPF: HELO does not publish an SPF Record
 SPF_PASS               -0.001 SPF: sender matches SPF record
Subject: Re: [pbs-devel] [pve-devel] [PATCH v2 proxmox-backup-qemu 05/11]
 access: use bigger cache and LRU chunk reader
X-BeenThere: pbs-devel@lists.proxmox.com
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Proxmox Backup Server development discussion
 <pbs-devel.lists.proxmox.com>
List-Unsubscribe: <https://lists.proxmox.com/cgi-bin/mailman/options/pbs-devel>, 
 <mailto:pbs-devel-request@lists.proxmox.com?subject=unsubscribe>
List-Archive: <http://lists.proxmox.com/pipermail/pbs-devel/>
List-Post: <mailto:pbs-devel@lists.proxmox.com>
List-Help: <mailto:pbs-devel-request@lists.proxmox.com?subject=help>
List-Subscribe: <https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel>, 
 <mailto:pbs-devel-request@lists.proxmox.com?subject=subscribe>
X-List-Received-Date: Wed, 17 Mar 2021 16:03:57 -0000

What about using a memory mapped files as cache. That way, you do not
need to care about available memory?

> >> Maybe we could get the available memory and use that as hint, I mean as memory
> >> usage can be highly dynamic it will never be perfect, but better than just ignoring
> >> it..
> > 
> > If anything, I'd make it user-configurable - I don't think a heuristic would be a good choice here.
> 
> Yeah, heuristic is not an good option as we cannot know how the system memory
> situation will be in the future.