Date: Tue, 13 Nov 2012 00:19:25 -0800 (PST)
From: David Rientjes <rientjes@google.com>
To: Cyrill Gorcunov <gorcunov@openvz.org>
cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Pavel Emelyanov <xemul@parallels.com>,
        James Bottomley <jbottomley@parallels.com>,
        Matthew Helsley <matt.helsley@gmail.com>,
        aneesh.kumar@linux.vnet.ibm.com, bfields@fieldses.org
Subject: Re: [patch 3/7] fs, notify: Add file handle entry into
 inotify_inode_mark
In-Reply-To: <20121113080032.GF6511@moon>
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References: <20121112101440.665694060@openvz.org> <20121112101845.839702715@openvz.org> <20121112165540.2ec39f50.akpm@linux-foundation.org> <20121113072057.GC6511@moon> <20121112234001.009b2ae3.akpm@linux-foundation.org> <20121113080032.GF6511@moon>
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On Tue, 13 Nov 2012, Cyrill Gorcunov wrote:

> > The question is, how many `struct inotify_inode_mark's are instantiated
> > system-wide?  Could be millions?
> 
> Well, hard to tell, to be fair. On my testing machine only apache has been
> using inotify system as far as I remember, but for sure nothing except memory
> limit the number of inotify. But I think if one running machine with millions
> of inotify it's rather powerful machine with enough memory.
> 

Seems easy to determine if you boot with slub_nomerge on the command line 
and then read /sys/kernel/slab/inotify_inode_mark/objects.  On my system, 
that happens to be 210, but I'm sure you could come up with a realistic 
synthetic workload to make it much higher.
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