From: Eric B Munson <emunson@mgebm.net>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.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>,
David Miller <davem@davemloft.net>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Neil Brown <neilb@suse.de>, Christoph Hellwig <hch@infradead.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Mike Christie <michaelc@cs.wisc.edu>,
Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Subject: Re: [PATCH 00/12] Swap-over-NFS without deadlocking V8
Date: Sun, 1 Jul 2012 13:22:54 -0400 [thread overview]
Message-ID: <20120701172254.GB2470@mgebm.net> (raw)
In-Reply-To: <1340976805-5799-1-git-send-email-mgorman@suse.de>
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On Fri, 29 Jun 2012, Mel Gorman wrote:
> Changelog since V7
> o Rebase to linux-next 20120629
> o bi->page_dma instead of bi->page in intel driver
> o Build fix for !CONFIG_NET (sebastian)
> o Restore PF_MEMALLOC flags correctly in all cases (jlayton)
>
> Changelog since V6
> o Rebase to linux-next 20120622
>
> Changelog since V5
> o Rebase to v3.5-rc3
>
> Changelog since V4
> o Catch if SOCK_MEMALLOC flag is cleared with rmem tokens (davem)
>
> Changelog since V3
> o Rebase to 3.4-rc5
> o kmap pages for writing to swap (akpm)
> o Move forward declaration to reduce chance of duplication (akpm)
>
> Changelog since V2
> o Nothing significant, just rebases. A radix tree lookup is replaced with
> a linear search would be the biggest rebase artifact
>
> This patch series is based on top of "Swap-over-NBD without deadlocking v14"
> as it depends on the same reservation of PF_MEMALLOC reserves logic.
>
> When a user or administrator requires swap for their application, they
> create a swap partition and file, format it with mkswap and activate it with
> swapon. In diskless systems this is not an option so if swap if required
> then swapping over the network is considered. The two likely scenarios
> are when blade servers are used as part of a cluster where the form factor
> or maintenance costs do not allow the use of disks and thin clients.
>
> The Linux Terminal Server Project recommends the use of the Network
> Block Device (NBD) for swap but this is not always an option. There is
> no guarantee that the network attached storage (NAS) device is running
> Linux or supports NBD. However, it is likely that it supports NFS so there
> are users that want support for swapping over NFS despite any performance
> concern. Some distributions currently carry patches that support swapping
> over NFS but it would be preferable to support it in the mainline kernel.
>
> Patch 1 avoids a stream-specific deadlock that potentially affects TCP.
>
> Patch 2 is a small modification to SELinux to avoid using PFMEMALLOC
> reserves.
>
> Patch 3 adds three helpers for filesystems to handle swap cache pages.
> For example, page_file_mapping() returns page->mapping for
> file-backed pages and the address_space of the underlying
> swap file for swap cache pages.
>
> Patch 4 adds two address_space_operations to allow a filesystem
> to pin all metadata relevant to a swapfile in memory. Upon
> successful activation, the swapfile is marked SWP_FILE and
> the address space operation ->direct_IO is used for writing
> and ->readpage for reading in swap pages.
>
> Patch 5 notes that patch 3 is bolting
> filesystem-specific-swapfile-support onto the side and that
> the default handlers have different information to what
> is available to the filesystem. This patch refactors the
> code so that there are generic handlers for each of the new
> address_space operations.
>
> Patch 6 adds an API to allow a vector of kernel addresses to be
> translated to struct pages and pinned for IO.
>
> Patch 7 adds support for using highmem pages for swap by kmapping
> the pages before calling the direct_IO handler.
>
> Patch 8 updates NFS to use the helpers from patch 3 where necessary.
>
> Patch 9 avoids setting PF_private on PG_swapcache pages within NFS.
>
> Patch 10 implements the new swapfile-related address_space operations
> for NFS and teaches the direct IO handler how to manage
> kernel addresses.
>
> Patch 11 prevents page allocator recursions in NFS by using GFP_NOIO
> where appropriate.
>
> Patch 12 fixes a NULL pointer dereference that occurs when using
> swap-over-NFS.
>
> With the patches applied, it is possible to mount a swapfile that is on an
> NFS filesystem. Swap performance is not great with a swap stress test taking
> roughly twice as long to complete than if the swap device was backed by NBD.
To test this set I am using memory cgroups to force swap usage. I am seeing
the cgroup controller killing my processes instead of using the nfs swapfile.
I am not yet sure if I am making a silly mistake or if something else is wrong.
Eric
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next prev parent reply other threads:[~2012-07-01 17:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 13:33 Mel Gorman
2012-06-29 13:33 ` [PATCH 01/12] netvm: Prevent a stream-specific deadlock Mel Gorman
2012-06-29 13:33 ` [PATCH 02/12] selinux: tag avc cache alloc as non-critical Mel Gorman
2012-06-29 13:33 ` [PATCH 03/12] mm: Methods for teaching filesystems about PG_swapcache pages Mel Gorman
2012-06-29 13:33 ` [PATCH 04/12] mm: Add support for a filesystem to activate swap files and use direct_IO for writing swap pages Mel Gorman
2012-06-29 13:33 ` [PATCH 05/12] mm: swap: Implement generic handler for swap_activate Mel Gorman
2012-06-29 13:33 ` [PATCH 06/12] mm: Add get_kernel_page[s] for pinning of kernel addresses for I/O Mel Gorman
2012-06-29 13:33 ` [PATCH 07/12] mm: Add support for direct_IO to highmem pages Mel Gorman
2012-06-29 13:33 ` [PATCH 08/12] nfs: teach the NFS client how to treat PG_swapcache pages Mel Gorman
2012-06-29 13:33 ` [PATCH 09/12] nfs: disable data cache revalidation for swapfiles Mel Gorman
2012-06-29 13:33 ` [PATCH 10/12] nfs: enable swap on NFS Mel Gorman
2012-06-29 13:33 ` [PATCH 11/12] nfs: Prevent page allocator recursions with swap over NFS Mel Gorman
2012-06-29 13:33 ` [PATCH 12/12] Avoid dereferencing bd_disk during swap_entry_free for network storage Mel Gorman
2012-07-01 17:22 ` Eric B Munson [this message]
2012-07-02 14:35 ` [PATCH 00/12] Swap-over-NFS without deadlocking V8 Mel Gorman
2012-07-03 0:10 ` Eric B Munson
2012-07-03 8:58 ` Mel Gorman
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