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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <1017390.1628158757@warthog.procyon.org.uk> <1170464.1628168823@warthog.procyon.org.uk> <1186271.1628174281@warthog.procyon.org.uk> <1219713.1628181333@warthog.procyon.org.uk> To: Matthew Wilcox Cc: dhowells@redhat.com, Anna Schumaker , Trond Myklebust , Jeff Layton , Steve French , Dominique Martinet , Mike Marshall , Miklos Szeredi , Shyam Prasad N , Linus Torvalds , linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, devel@lists.orangefs.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Canvassing for network filesystem write size vs page size MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1302764.1628257488.1@warthog.procyon.org.uk> Date: Fri, 06 Aug 2021 14:44:48 +0100 Message-ID: <1302765.1628257488@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=N6El3VVj; spf=none (imf09.hostedemail.com: domain of dhowells@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=dhowells@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: AB9CB300AB8A X-Stat-Signature: o7m9qzwys4bkudgtwzt8e9t5us4jtme6 X-HE-Tag: 1628257504-804376 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Matthew Wilcox wrote: > Filesystems should not make an assumption about this ... I suspect > the optimum page size scales with I/O bandwidth; taking PCI bandwidth > as a reasonable proxy, it's doubled five times in twenty years. There are a lot more factors than you make out. Local caching, content crypto, transport crypto, cost of setting up RPC calls, compounding calls to multiple servers. David