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From:   "NeilBrown" <neilb@suse.de>
To:     "Zygo Blaxell" <ce3g8jdj@umail.furryterror.org>
Cc:     "J. Bruce Fields" <bfields@fieldses.org>,
        "Neal Gompa" <ngompa13@gmail.com>,
        "Wang Yugui" <wangyugui@e16-tech.com>,
        "Christoph Hellwig" <hch@infradead.org>,
        "Josef Bacik" <josef@toxicpanda.com>,
        "Chuck Lever" <chuck.lever@oracle.com>, "Chris Mason" <clm@fb.com>,
        "David Sterba" <dsterba@suse.com>,
        "Alexander Viro" <viro@zeniv.linux.org.uk>,
        "linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
        linux-nfs@vger.kernel.org,
        "Btrfs BTRFS" <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH/RFC 00/11] expose btrfs subvols in mount table correctly
In-reply-to: <20210729012931.GK10170@hungrycats.org>
References: <162742539595.32498.13687924366155737575.stgit@noble.brown>,
 <20210728125819.6E52.409509F4@e16-tech.com>,
 <20210728140431.D704.409509F4@e16-tech.com>,
 <162745567084.21659.16797059962461187633@noble.neil.brown.name>,
 <CAEg-Je8Pqbw0tTw6NWkAcD=+zGStOJR0J-409mXuZ1vmb6dZsA@mail.gmail.com>,
 <20210728191431.GA3152@fieldses.org>, <20210729012931.GK10170@hungrycats.org>
Date:   Thu, 29 Jul 2021 11:43:21 +1000
Message-id: <162752300106.21659.7482208502904653864@noble.neil.brown.name>
Precedence: bulk

On Thu, 29 Jul 2021, Zygo Blaxell wrote:
> 
> I'm looking at a few machines here, and if all the subvols are visible to
> 'df', its output would be somewhere around 3-5 MB.  That's too much--we'd
> have to hack up df to not show the same btrfs twice...as well as every
> monitoring tool that reports free space...which sounds similar to the
> problems we're trying to avoid.

Thanks for providing hard data!! How many of these subvols are actively
used (have a file open) a the same time? Most? About half? Just a few??

Thanks,
NeilBrown