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Date:   Tue, 9 Feb 2021 22:01:27 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     "mgorman@suse.de" <mgorman@suse.de>,
        "brouer@redhat.com" <brouer@redhat.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: Fwd: alloc_pages_bulk()
Message-ID: <20210209220127.GB308988@casper.infradead.org>
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On Mon, Feb 08, 2021 at 05:50:51PM +0000, Chuck Lever wrote:
> > We've been discussing how NFSD can more efficiently refill its
> > receive buffers (currently alloc_page() in a loop; see
> > net/sunrpc/svc_xprt.c::svc_alloc_arg()).

I'm not familiar with the sunrpc architecture, but this feels like you're
trying to optimise something that shouldn't exist.  Ideally a write
would ask the page cache for the pages that correspond to the portion
of the file which is being written to.  I appreciate that doesn't work
well for, eg, NFS-over-TCP, but for NFS over any kind of RDMA, that
should be possible, right?