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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20200330211700.g7evnuvvjenq3fzm@wittgenstein> <1445647.1585576702@warthog.procyon.org.uk> <2418286.1585691572@warthog.procyon.org.uk> <20200401144109.GA29945@gardel-login> To: Miklos Szeredi Cc: dhowells@redhat.com, Lennart Poettering , Christian Brauner , Linus Torvalds , Al Viro , dray@redhat.com, Karel Zak , Miklos Szeredi , Steven Whitehouse , Jeff Layton , Ian Kent , andres@anarazel.de, keyrings@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Aleksa Sarai Subject: Re: Upcoming: Notifications, FS notifications and fsinfo() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2590639.1585757211.1@warthog.procyon.org.uk> Date: Wed, 01 Apr 2020 17:06:51 +0100 Message-ID: <2590640.1585757211@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Miklos Szeredi wrote: > I've still not heard a convincing argument in favor of a syscall. From your own results, scanning 10000 mounts through mountfs and reading just two values from each is an order of magnitude slower without the effect of the dentry/inode caches. It gets faster on the second run because the mountfs dentries and inodes are cached - but at a cost of >205MiB of RAM. And it's *still* slower than fsinfo(). David