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Message-Id: <1195571680.5041.14.camel@localhost>
Date: Tue, 20 Nov 2007 10:14:39 -0500
From: Lee Schermerhorn <Lee.Schermerhorn@...com>
To: Mel Gorman <mel@....ul.ie>
Cc: Christoph Lameter <clameter@....com>, akpm@...ux-foundation.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
rientjes@...gle.com, nacc@...ibm.com,
kamezawa.hiroyu@...fujitsu.com
Subject: Re: [PATCH 6/6] Use one zonelist that is filtered by nodemask
On Tue, 2007-11-20 at 14:19 +0000, Mel Gorman wrote:
> On (09/11/07 07:45), Christoph Lameter didst pronounce:
> > On Fri, 9 Nov 2007, Mel Gorman wrote:
> >
> > > struct page * fastcall
> > > __alloc_pages(gfp_t gfp_mask, unsigned int order,
> > > struct zonelist *zonelist)
> > > {
> > > + /*
> > > + * Use a temporary nodemask for __GFP_THISNODE allocations. If the
> > > + * cost of allocating on the stack or the stack usage becomes
> > > + * noticable, allocate the nodemasks per node at boot or compile time
> > > + */
> > > + if (unlikely(gfp_mask & __GFP_THISNODE)) {
> > > + nodemask_t nodemask;
> >
> > Hmmm.. This places a potentially big structure on the stack. nodemask can
> > contain up to 1024 bits which means 128 bytes. Maybe keep an array of
> > gfp_thisnode nodemasks (node_nodemask?) and use node_nodemask[nid]?
>
> Went back and revisited this. Allocating them at boot-time is below but
> essentially it is a silly and it makes sense to just have two zonelists
> where one of them is for __GFP_THISNODE. Implementation wise, this involves
> dropping the last patch in the set and the overall result is still a reduction
> in the number of zonelists.
Hi, Mel:
I'll try this out [n 24-rc2-mm1 or later]. I have a series with yet
another rework of policy reference counting that will be easier/cleaner
atop your series w/o the external zonelist hung off 'BIND policies. So,
I'm hoping your series goes into -mm "real soon now".
Question: Just wondering why you didn't embed the '_THISNODE nodemask
in the pgdat_t--initialized at boot/node-hot-add time? Perhaps under
#ifdef CONFIG_NUMA. The size is known at build time, right? And
wouldn't that be way smaller than an additional zonelist?
Lee
>
> diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.24-rc2-mm1-040_use_one_zonelist/include/linux/gfp.h linux-2.6.24-rc2-mm1-045_use_static_nodemask/include/linux/gfp.h
> --- linux-2.6.24-rc2-mm1-040_use_one_zonelist/include/linux/gfp.h 2007-11-19 19:27:15.000000000 +0000
> +++ linux-2.6.24-rc2-mm1-045_use_static_nodemask/include/linux/gfp.h 2007-11-19 19:28:55.000000000 +0000
> @@ -175,7 +175,6 @@ FASTCALL(__alloc_pages(gfp_t, unsigned i
> extern struct page *
> FASTCALL(__alloc_pages_nodemask(gfp_t, unsigned int,
> struct zonelist *, nodemask_t *nodemask));
> -extern nodemask_t *nodemask_thisnode(int nid, nodemask_t *nodemask);
>
> static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
> unsigned int order)
> @@ -187,13 +186,10 @@ static inline struct page *alloc_pages_n
> if (nid < 0)
> nid = numa_node_id();
>
> - /* Use a temporary nodemask for __GFP_THISNODE allocations */
> if (unlikely(gfp_mask & __GFP_THISNODE)) {
> - nodemask_t nodemask;
> -
> return __alloc_pages_nodemask(gfp_mask, order,
> node_zonelist(nid),
> - nodemask_thisnode(nid, &nodemask));
> + NODE_DATA(nid)->nodemask_thisnode);
> }
>
> return __alloc_pages(gfp_mask, order, node_zonelist(nid));
> diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.24-rc2-mm1-040_use_one_zonelist/include/linux/mmzone.h linux-2.6.24-rc2-mm1-045_use_static_nodemask/include/linux/mmzone.h
> --- linux-2.6.24-rc2-mm1-040_use_one_zonelist/include/linux/mmzone.h 2007-11-19 19:27:15.000000000 +0000
> +++ linux-2.6.24-rc2-mm1-045_use_static_nodemask/include/linux/mmzone.h 2007-11-19 19:28:55.000000000 +0000
> @@ -519,6 +519,9 @@ typedef struct pglist_data {
> struct zone node_zones[MAX_NR_ZONES];
> struct zonelist node_zonelist;
> int nr_zones;
> +
> + /* nodemask suitable for __GFP_THISNODE */
> + nodemask_t *nodemask_thisnode;
> #ifdef CONFIG_FLAT_NODE_MEM_MAP
> struct page *node_mem_map;
> #endif
> diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.24-rc2-mm1-040_use_one_zonelist/mm/page_alloc.c linux-2.6.24-rc2-mm1-045_use_static_nodemask/mm/page_alloc.c
> --- linux-2.6.24-rc2-mm1-040_use_one_zonelist/mm/page_alloc.c 2007-11-19 19:27:15.000000000 +0000
> +++ linux-2.6.24-rc2-mm1-045_use_static_nodemask/mm/page_alloc.c 2007-11-19 19:28:55.000000000 +0000
> @@ -1695,28 +1695,36 @@ got_pg:
> }
>
> /* Creates a nodemask suitable for GFP_THISNODE allocations */
> -nodemask_t *nodemask_thisnode(int nid, nodemask_t *nodemask)
> +static inline void alloc_node_nodemask_thisnode(pg_data_t *pgdat)
> {
> - nodes_clear(*nodemask);
> - node_set(nid, *nodemask);
> + nodemask_t *nodemask_thisnode;
>
> - return nodemask;
> + /* Only a machine with multiple nodes needs the nodemask */
> + if (!NUMA_BUILD || num_online_nodes() == 1)
> + return;
> +
> + /* Allocate the nodemask. Serious if it fails, but not world ending */
> + nodemask_thisnode = alloc_bootmem_node(pgdat, sizeof(nodemask_t));
> + if (!nodemask_thisnode) {
> + printk(KERN_WARNING
> + "thisnode nodemask allocation failed."
> + "There may be sub-optimal NUMA placement.\n");
> + return;
> + }
> +
> + /* Initialise the nodemask to only cover the current node */
> + nodes_clear(*nodemask_thisnode);
> + node_set(pgdat->node_id, *nodemask_thisnode);
> + pgdat->nodemask_thisnode = nodemask_thisnode;
> }
>
> struct page * fastcall
> __alloc_pages(gfp_t gfp_mask, unsigned int order,
> struct zonelist *zonelist)
> {
> - /*
> - * Use a temporary nodemask for __GFP_THISNODE allocations. If the
> - * cost of allocating on the stack or the stack usage becomes
> - * noticable, allocate the nodemasks per node at boot or compile time
> - */
> if (unlikely(gfp_mask & __GFP_THISNODE)) {
> - nodemask_t nodemask;
> -
> - return __alloc_pages_internal(gfp_mask, order,
> - zonelist, nodemask_thisnode(numa_node_id(), &nodemask));
> + return __alloc_pages_internal(gfp_mask, order, zonelist,
> + NODE_DATA(numa_node_id())->nodemask_thisnode);
> }
>
> return __alloc_pages_internal(gfp_mask, order, zonelist, NULL);
> @@ -3501,6 +3509,7 @@ void __meminit free_area_init_node(int n
> calculate_node_totalpages(pgdat, zones_size, zholes_size);
>
> alloc_node_mem_map(pgdat);
> + alloc_node_nodemask_thisnode(pgdat);
>
> free_area_init_core(pgdat, zones_size, zholes_size);
> }
>
-
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