lkml.org 
[lkml]   [2008]   [Mar]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: allocate section_map for sparse_init
On Tue, Mar 18, 2008 at 2:41 AM, Mel Gorman <mel@csn.ul.ie> wrote:
> On (13/03/08 11:02), Yinghai Lu didst pronounce:
>
>
> > On Thu, Mar 13, 2008 at 4:19 AM, Mel Gorman <mel@csn.ul.ie> wrote:
> > > On (12/03/08 10:51), Yinghai Lu didst pronounce:
> > >
> > >
> > > > [PATCH] mm: allocate section_map for sparse_init
> > > >
> > > > allocate section_map in bootmem instead of using __initdata.
> > > >
> > > > need to apply it after
> > > > [PATCH] mm: fix boundary checking in free_bootmem_core
> > > > [PATCH] mm: make mem_map allocation continuous.
> > > >
> > > >
> > > > Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
> > >
> > > > Index: linux-2.6/mm/sparse.c
> > > > ===================================================================
> > > > --- linux-2.6.orig/mm/sparse.c
> > > > +++ linux-2.6/mm/sparse.c
> > > > @@ -285,8 +285,6 @@ struct page __init *sparse_early_mem_map
> > > > return NULL;
> > > > }
> > > >
> > > > -/* section_map pointer array is 64k */
> > > > -static __initdata struct page *section_map[NR_MEM_SECTIONS];
> > > > /*
> > > > * Allocate the accumulated non-linear sections, allocate a mem_map
> > > > * for each and record the physical to section mapping.
> > > > @@ -296,6 +294,9 @@ void __init sparse_init(void)
> > > > unsigned long pnum;
> > > > struct page *map;
> > > > unsigned long *usemap;
> > > > + struct page **section_map;
> > > > + int size;
> > > > + int node;
> > > >
> > > > /*
> > > > * map is using big page (aka 2M in x86 64 bit)
> > > > @@ -305,13 +306,17 @@ void __init sparse_init(void)
> > > > * then in big system, the memmory will have a lot hole...
> > > > * here try to allocate 2M pages continously.
> > > > */
> > > > + size = sizeof(struct page *) * NR_MEM_SECTIONS;
> > > > + section_map = alloc_bootmem(size);
> > > > + if (!section_map)
> > > > + panic("can not allocate section_map\n");
> > > > +
> > > > for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
> > > > if (!present_section_nr(pnum))
> > > > continue;
> > > > section_map[pnum] = sparse_early_mem_map_alloc(pnum);
> > > > }
> > > >
> > > > -
> > > > for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
> > > > if (!present_section_nr(pnum))
> > > > continue;
> > > > @@ -327,6 +332,9 @@ void __init sparse_init(void)
> > > > sparse_init_one_section(__nr_to_section(pnum), pnum, map,
> > > > usemap);
> > > > }
> > > > +
> > > > + for_each_online_node(node)
> > > > + free_bootmem_node(NODE_DATA(node), __pa(section_map), size);
> > >
> > > Why are you iterating every online node here instead of just calling
> > > free_bootmem(__pa(section_map), size) ?
> >
> > free_bootmem will assume use bdata on NODE_DATA(0).
> >
>
> True. The unwritten assumption is that NODE_DATA(0) always has memory
> for allocate or free.
>
>
> > some cases: four nodes system: only have memory installed for node 1,
> > and node 3.
> > alloc_bootmem will loop to get bootmem from node1, because there is no
> > ram node0, and not NODE_DATA(0) ...
> >
> > we may update free_bootmem to loop all bdata or all online nodes to
> > call free_bootmem_core...
> >
>
> Alternatively, update free_bootmem so that it figures out which node it is
> meant to be freeing to based on the PFN of the page currently being freed.
>
> It still doesn't seem right to try freeing on all online nodes as it looks like
> free_bootmem_core() should flip bits outside the range of its node_bootmem_map
> which could cause tricky bugs.
>
> As things currently stand with bootmem, what you should be doing is using
> for_each_online_node() to figure out which node you can allocate from,
> remembering that node and calling free_bootmem_node() once. If you fix
> free_bootmem() though, you should only need to call free_bootmem() once
> in this patch.

Yes

with the new free_bootmem that loop bdata_list, we can call
free_bootmem.

YH


\
 
 \ /
  Last update: 2008-03-20 00:55    [W:0.045 / U:1.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site