From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>,
Linux-MM <linux-mm@kvack.org>,
Linux-Netdev <netdev@vger.kernel.org>,
Linux-NFS <linux-nfs@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Neil Brown <neilb@suse.de>
Subject: Re: [PATCH 03/10] mm: Add support for a filesystem to control swap files
Date: Mon, 12 Sep 2011 12:56:05 +0100 [thread overview]
Message-ID: <20110912115605.GB3207@suse.de> (raw)
In-Reply-To: <1315821369.26517.21.camel@twins>
On Mon, Sep 12, 2011 at 11:56:09AM +0200, Peter Zijlstra wrote:
> On Mon, 2011-09-12 at 10:34 +0100, Mel Gorman wrote:
> > On Mon, Sep 12, 2011 at 11:04:45AM +0200, Peter Zijlstra wrote:
> > > On Fri, 2011-09-09 at 09:36 -0400, Christoph Hellwig wrote:
> > > > The equivalent of ->direct_IO should be used for both reads and writes.
> > >
> > > So the difference between DIO and swapIO is that swapIO needs the block
> > > map pinned in memory.. So at the very least you'll need those
> > > swap_{activate,deactivate} aops. The read/write-page thingies could
> > > indeed be shared with DIO.
> > >
> >
> > I'm travelling at the moment so it'll be later in the week when I investigate
> > properly but I agree swap_[de|a]ctivate are still necessary. NFS does not
> > need to pin a block map but it's still necessary for calling xs_set_memalloc.
>
> Right.. but I think the hope was that we could replace the current swap
> bmap hackery with this and simplify the normal swap bits. But yeah,
> networked filesystems don't really bother with block maps on the client
> side ;-)
I took a look at what was involved with doing the block lookups in
ext4. It's what led to patch 4 of this series because it was necessary that
the filesystem get the same information as the generic handler. It got a
bit messy but looked like it would have worked if I kept at it. I stopped
because I did nt see a major advantage with swap_writepage() looking up
the block map instead of having looked it up in advance with bmap() but
I could have missed something.
WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>,
Linux-MM <linux-mm@kvack.org>,
Linux-Netdev <netdev@vger.kernel.org>,
Linux-NFS <linux-nfs@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Neil Brown <neilb@suse.de>
Subject: Re: [PATCH 03/10] mm: Add support for a filesystem to control swap files
Date: Mon, 12 Sep 2011 12:56:05 +0100 [thread overview]
Message-ID: <20110912115605.GB3207@suse.de> (raw)
In-Reply-To: <1315821369.26517.21.camel@twins>
On Mon, Sep 12, 2011 at 11:56:09AM +0200, Peter Zijlstra wrote:
> On Mon, 2011-09-12 at 10:34 +0100, Mel Gorman wrote:
> > On Mon, Sep 12, 2011 at 11:04:45AM +0200, Peter Zijlstra wrote:
> > > On Fri, 2011-09-09 at 09:36 -0400, Christoph Hellwig wrote:
> > > > The equivalent of ->direct_IO should be used for both reads and writes.
> > >
> > > So the difference between DIO and swapIO is that swapIO needs the block
> > > map pinned in memory.. So at the very least you'll need those
> > > swap_{activate,deactivate} aops. The read/write-page thingies could
> > > indeed be shared with DIO.
> > >
> >
> > I'm travelling at the moment so it'll be later in the week when I investigate
> > properly but I agree swap_[de|a]ctivate are still necessary. NFS does not
> > need to pin a block map but it's still necessary for calling xs_set_memalloc.
>
> Right.. but I think the hope was that we could replace the current swap
> bmap hackery with this and simplify the normal swap bits. But yeah,
> networked filesystems don't really bother with block maps on the client
> side ;-)
I took a look at what was involved with doing the block lookups in
ext4. It's what led to patch 4 of this series because it was necessary that
the filesystem get the same information as the generic handler. It got a
bit messy but looked like it would have worked if I kept at it. I stopped
because I did nt see a major advantage with swap_writepage() looking up
the block map instead of having looked it up in advance with bmap() but
I could have missed something.
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next prev parent reply other threads:[~2011-09-12 11:56 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-09 11:00 [RFC PATCH 00/10] Swap-over-NFS without deadlocking v1 Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 01/10] netvm: Prevent a stream-specific deadlock Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 02/10] selinux: tag avc cache alloc as non-critical Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 03/10] mm: Add support for a filesystem to control swap files Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 13:00 ` Christoph Hellwig
2011-09-09 13:00 ` Christoph Hellwig
2011-09-09 13:00 ` Christoph Hellwig
2011-09-09 13:15 ` Mel Gorman
2011-09-09 13:15 ` Mel Gorman
2011-09-09 13:36 ` Christoph Hellwig
2011-09-09 13:36 ` Christoph Hellwig
2011-09-12 9:04 ` Peter Zijlstra
2011-09-12 9:04 ` Peter Zijlstra
2011-09-12 9:34 ` Mel Gorman
2011-09-12 9:34 ` Mel Gorman
2011-09-12 9:34 ` Mel Gorman
2011-09-12 9:56 ` Peter Zijlstra
2011-09-12 9:56 ` Peter Zijlstra
2011-09-12 11:56 ` Mel Gorman [this message]
2011-09-12 11:56 ` Mel Gorman
2011-09-12 12:06 ` Peter Zijlstra
2011-09-12 12:06 ` Peter Zijlstra
2011-09-09 11:00 ` [PATCH 04/10] mm: swap: Implement generic handlers for swap-related address ops Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 05/10] mm: Methods for teaching filesystems about PG_swapcache pages Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 06/10] nfs: teach the NFS client how to treat " Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 07/10] nfs: disable data cache revalidation for swapfiles Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 08/10] nfs: enable swap on NFS Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 09/10] nfs: Prevent page allocator recursions with swap over NFS Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 11:00 ` [PATCH 10/10] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman
2011-09-09 11:00 ` Mel Gorman
2011-09-09 13:02 ` Christoph Hellwig
2011-09-09 13:02 ` Christoph Hellwig
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