Re: [PATCH 0/6] Use two zonelists per node instead of multiplezonelists v11r2

[Lee Schermerhorn]

On Tue, 2007-12-11 at 20:21 +0000, Mel Gorman wrote:
> This is a rebase of the two-zonelist patchset to 2.6.24-rc4-mm1 and some
> warnings cleared up. The warnings were not picked up before as they were
> introduced early in the set and cleared up by the end. This might have hurt
> bisecting so were worth fixing even if the end result was correct. Tests
> looked good, both numactltest (slightly modified) and performance tests.
> 
> I believe Lee has been testing heavily with a version of the patchset
> almost identical to this and hasn't complained. If Lee is happy enough,
> can you merge these to -mm for wider testing please Andrew?

Mel, Andrew:

Yes, I have been testing Mel's series quite heavily.  I've been testing
them stand along and with my recently post Memory Policy series for
"correctness: of page placement.  I've also rebased my shared policy and
automatic/lazy page migration patches along with Nick Piggin's pagecache
replication patch atop the twozonelist and mempolicy series and have
been doing some fairly heavy stress testing on an AMD x86_64 4 socket [4
node] dual core system.  Mel's patches are holding up well.

Just this afternoon, I hit a null pointer deref in
__mem_cgroup_remove_list() [called from mem_cgroup_uncharge() if I can
trust the stack trace] attempting to unmap a page for migration.  I'm
just starting to investigate this.

I'll replace the series I have [~V10] with V11r2 and continue testing in
anticipation of the day that we can get this into -mm.

Regards,
Lee

> 
> Changelog since V10
>   o Rebase to 2.6.24-rc4-mm1
>   o Clear up warnings in fs/buffer.c early in the patchset
> 
> Changelog since V9
>   o Rebase to 2.6.24-rc2-mm1
>   o Lookup the nodemask for each allocator callsite in mempolicy.c
>   o Update NUMA statistics based on preferred zone, not first zonelist entry
>   o When __GFP_THISNODE is specified with MPOL_BIND and the current node is
>     not in the allowed nodemask, the first node in the mask will be used
>   o Stick with using two zonelists instead of one because of excessive
>     complexity with corner cases
> 
> Changelog since V8
>   o Rebase to 2.6.24-rc2
>   o Added ack for the OOM changes
>   o Behave correctly when GFP_THISNODE and a node ID are specified
>   o Clear up warning over type of nodes_intersects() function
> 
> Changelog since V7
>   o Rebase to 2.6.23-rc8-mm2
> 
> Changelog since V6
>   o Fix build bug in relation to memory controller combined with one-zonelist
>   o Use while() instead of a stupid looking for()
>   o Instead of encoding zone index information in a pointer, this version
>     introduces a structure that stores a zone pointer and its index 
> 
> Changelog since V5
>   o Rebase to 2.6.23-rc4-mm1
>   o Drop patch that replaces inline functions with macros
> 
> Changelog since V4
>   o Rebase to -mm kernel. Host of memoryless patches collisions dealt with
>   o Do not call wakeup_kswapd() for every zone in a zonelist
>   o Dropped the FASTCALL removal
>   o Have cursor in iterator advance earlier
>   o Use nodes_and in cpuset_nodes_valid_mems_allowed()
>   o Use defines instead of inlines, noticably better performance on gcc-3.4
>     No difference on later compilers such as gcc 4.1
>   o Dropped gfp_skip patch until it is proven to be of benefit. Tests are
>     currently inconclusive but it definitly consumes at least one cache
>     line
> 
> Changelog since V3
>   o Fix compile error in the parisc change
>   o Calculate gfp_zone only once in __alloc_pages
>   o Calculate classzone_idx properly in get_page_from_freelist
>   o Alter check so that zone id embedded may still be used on UP
>   o Use Kamezawa-sans suggestion for skipping zones in zonelist
>   o Add __alloc_pages_nodemask() to filter zonelist based on a nodemask. This
>     removes the need for MPOL_BIND to have a custom zonelist
>   o Move zonelist iterators and helpers to mm.h
>   o Change _zones from struct zone * to unsigned long
>   
> Changelog since V2
>   o shrink_zones() uses zonelist instead of zonelist->zones
>   o hugetlb uses zonelist iterator
>   o zone_idx information is embedded in zonelist pointers
>   o replace NODE_DATA(nid)->node_zonelist with node_zonelist(nid)
> 
> Changelog since V1
>   o Break up the patch into 3 patches
>   o Introduce iterators for zonelists
>   o Performance regression test
> 
> The following patches replace multiple zonelists per node with two zonelists
> that are filtered based on the GFP flags. The patches as a set fix a bug
> with regard to the use of MPOL_BIND and ZONE_MOVABLE. With this patchset,
> the MPOL_BIND will apply to the two highest zones when the highest zone
> is ZONE_MOVABLE. This should be considered as an alternative fix for the
> MPOL_BIND+ZONE_MOVABLE in 2.6.23 to the previously discussed hack that
> filters only custom zonelists.
> 
> The first patch cleans up an inconsitency where direct reclaim uses
> zonelist->zones where other places use zonelist.
> 
> The second patch introduces a helper function node_zonelist() for looking
> up the appropriate zonelist for a GFP mask which simplifies patches later
> in the set.
> 
> The third patch replaces multiple zonelists with two zonelists that are
> filtered. The two zonelists are due to the fact that the memoryless patchset
> introduces a second set of zonelists for __GFP_THISNODE.
> 
> The fourth patch introduces helper macros for retrieving the zone and node indices of entries in a zonelist.
> 
> The final patch introduces filtering of the zonelists based on a nodemask. Two
> zonelists exist per node, one for normal allocations and one for __GFP_THISNODE.
> 
> Performance results varied depending on the machine configuration. In real
> workloads the gain/loss will depend on how much the userspace portion of
> the benchmark benefits from having more cache available due to reduced
> referencing of zonelists.
> 
> These are the range of performance losses/gains when running against
> 2.6.24-rc4-mm1. The set and these machines are a mix of i386, x86_64 and
> ppc64 both NUMA and non-NUMA.
> 
> 			     loss   to  gain
> Total CPU time on Kernbench: -0.86% to  1.13%
> Elapsed   time on Kernbench: -0.79% to  0.76%
> page_test from aim9:         -4.37% to  0.79%
> brk_test  from aim9:         -0.71% to  4.07%
> fork_test from aim9:         -1.84% to  4.60%
> exec_test from aim9:         -0.71% to  1.08%
> 

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