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From:   Mike Marshall <hubcap@omnibond.com>
Date:   Wed, 17 Feb 2021 11:59:15 -0500
Message-ID: <CAOg9mSTyFX+2MMSV77hLDUpHogQ=KXO5oNduA90FLoowPGk0Jw@mail.gmail.com>
Subject: Re: [PATCH 03/33] mm: Implement readahead_control pageset expansion
To:     David Howells <dhowells@redhat.com>
Cc:     Matthew Wilcox <willy@infradead.org>,
        Christoph Hellwig <hch@lst.de>,
        Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Steve French <sfrench@samba.org>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-mm <linux-mm@kvack.org>, linux-cachefs@redhat.com,
        linux-afs@lists.infradead.org,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        linux-cifs@vger.kernel.org,
        ceph-devel <ceph-devel@vger.kernel.org>,
        V9FS Developers <v9fs-developer@lists.sourceforge.net>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Jeff Layton <jlayton@redhat.com>,
        David Wysochanski <dwysocha@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>
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Precedence: bulk

Matthew has looked at how I'm fumbling about
trying to deal with Orangefs's need for much larger
than page-sized IO...

I think I need to implement orangefs_readahead
and from there fire off an asynchronous read
and while that's going I'll call readahead_page
with a rac that I've cranked up with readahead_expand
and when the read gets done I'll have plenty of pages
for the large IO I did.

Even if what I think I need to do is somewhere
near right, the async code in the Orangefs
kernel module didn't make it into the upstream
version, so I have to refurbish that. All that to
say: I don't need readahead_expand
"tomorrow", but it fits into my plan to
get Orangefs the extra pages it needs
without me having open-coded page cache
code in orangefs_readpage.

-Mike

On Wed, Feb 17, 2021 at 10:42 AM David Howells <dhowells@redhat.com> wrote:
>
> Mike Marshall <hubcap@omnibond.com> wrote:
>
> > I plan to try and use readahead_expand in Orangefs...
>
> Would it help if I shuffled the readahead_expand patch to the bottom of the
> pack?
>
> David
>