Messages in this thread Patch in this message | | | Date | Fri, 2 Oct 2009 15:16:18 +0100 | From | Mel Gorman <> | Subject | Re: [this_cpu_xx V4 12/20] Move early initialization of pagesets out of zone_wait_table_init() |
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On Thu, Oct 01, 2009 at 05:25:33PM -0400, cl@linux-foundation.org wrote: > Explicitly initialize the pagesets after the per cpu areas have been > initialized. This is necessary in order to be able to use per cpu > operations in later patches. >
Can you be more explicit about this? I think the reasoning is as follows
A later patch will use DEFINE_PER_CPU which allocates memory later in the boot-cycle after zones have already been initialised. Without this patch, use of DEFINE_PER_CPU would result in invalid memory accesses during pageset initialisation.
Have another question below as well.
> Cc: Mel Gorman <mel@csn.ul.ie> > Signed-off-by: Christoph Lameter <cl@linux-foundation.org> > > --- > arch/ia64/kernel/setup.c | 1 + > arch/powerpc/kernel/setup_64.c | 1 + > arch/sparc/kernel/smp_64.c | 1 + > arch/x86/kernel/setup_percpu.c | 2 ++ > include/linux/mm.h | 1 + > mm/page_alloc.c | 40 +++++++++++++++++++++++++++++----------- > mm/percpu.c | 2 ++ > 7 files changed, 37 insertions(+), 11 deletions(-) > > Index: linux-2.6/mm/page_alloc.c > =================================================================== > --- linux-2.6.orig/mm/page_alloc.c 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/mm/page_alloc.c 2009-10-01 09:36:19.000000000 -0500 > @@ -3270,23 +3270,42 @@ void zone_pcp_update(struct zone *zone) > stop_machine(__zone_pcp_update, zone, NULL); > } > > -static __meminit void zone_pcp_init(struct zone *zone) > +/* > + * Early setup of pagesets. > + * > + * In the NUMA case the pageset setup simply results in all zones pcp > + * pointer being directed at a per cpu pageset with zero batchsize. > + *
The batchsize becomes 1, not 0 if you look at setup_pageset() but that aside, it's unclear from the comment *why* the batchsize is 1 in the NUMA case. Maybe something like the following?
===== In the NUMA case, the boot_pageset is used until the slab allocator is available to allocate per-zone pagesets as each CPU is brought up. At this point, the batchsize is set to 1 to prevent pages "leaking" onto the boot_pageset freelists. =====
Otherwise, nothing in the patch jumped out at me other than to double check CPU-up events actually result in process_zones() being called and that boot_pageset is not being accidentally used in the long term.
> + * This means that every free and every allocation occurs directly from > + * the buddy allocator tables. > + * > + * The pageset never queues pages during early boot and is therefore usable > + * for every type of zone. > + */ > +__meminit void setup_pagesets(void) > { > int cpu; > - unsigned long batch = zone_batchsize(zone); > + struct zone *zone; > > - for (cpu = 0; cpu < NR_CPUS; cpu++) { > + for_each_zone(zone) { > #ifdef CONFIG_NUMA > - /* Early boot. Slab allocator not functional yet */ > - zone_pcp(zone, cpu) = &boot_pageset[cpu]; > - setup_pageset(&boot_pageset[cpu],0); > + unsigned long batch = 0; > + > + for (cpu = 0; cpu < NR_CPUS; cpu++) { > + /* Early boot. Slab allocator not functional yet */ > + zone_pcp(zone, cpu) = &boot_pageset[cpu]; > + } > #else > - setup_pageset(zone_pcp(zone,cpu), batch); > + unsigned long batch = zone_batchsize(zone); > #endif > + > + for_each_possible_cpu(cpu) > + setup_pageset(zone_pcp(zone, cpu), batch); > + > + if (zone->present_pages) > + printk(KERN_DEBUG " %s zone: %lu pages, LIFO batch:%lu\n", > + zone->name, zone->present_pages, batch); > } > - if (zone->present_pages) > - printk(KERN_DEBUG " %s zone: %lu pages, LIFO batch:%lu\n", > - zone->name, zone->present_pages, batch); > } > > __meminit int init_currently_empty_zone(struct zone *zone, > @@ -3841,7 +3860,6 @@ static void __paginginit free_area_init_ > > zone->prev_priority = DEF_PRIORITY; > > - zone_pcp_init(zone); > for_each_lru(l) { > INIT_LIST_HEAD(&zone->lru[l].list); > zone->reclaim_stat.nr_saved_scan[l] = 0; > Index: linux-2.6/include/linux/mm.h > =================================================================== > --- linux-2.6.orig/include/linux/mm.h 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/include/linux/mm.h 2009-10-01 09:36:19.000000000 -0500 > @@ -1060,6 +1060,7 @@ extern void show_mem(void); > extern void si_meminfo(struct sysinfo * val); > extern void si_meminfo_node(struct sysinfo *val, int nid); > extern int after_bootmem; > +extern void setup_pagesets(void); > > #ifdef CONFIG_NUMA > extern void setup_per_cpu_pageset(void); > Index: linux-2.6/arch/ia64/kernel/setup.c > =================================================================== > --- linux-2.6.orig/arch/ia64/kernel/setup.c 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/arch/ia64/kernel/setup.c 2009-10-01 09:35:39.000000000 -0500 > @@ -864,6 +864,7 @@ void __init > setup_per_cpu_areas (void) > { > /* start_kernel() requires this... */ > + setup_pagesets(); > } > #endif > > Index: linux-2.6/arch/powerpc/kernel/setup_64.c > =================================================================== > --- linux-2.6.orig/arch/powerpc/kernel/setup_64.c 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/arch/powerpc/kernel/setup_64.c 2009-10-01 09:35:39.000000000 -0500 > @@ -578,6 +578,7 @@ static void ppc64_do_msg(unsigned int sr > snprintf(buf, 128, "%s", msg); > ppc_md.progress(buf, 0); > } > + setup_pagesets(); > } > > /* Print a boot progress message. */ > Index: linux-2.6/arch/sparc/kernel/smp_64.c > =================================================================== > --- linux-2.6.orig/arch/sparc/kernel/smp_64.c 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/arch/sparc/kernel/smp_64.c 2009-10-01 09:35:39.000000000 -0500 > @@ -1486,4 +1486,5 @@ void __init setup_per_cpu_areas(void) > of_fill_in_cpu_data(); > if (tlb_type == hypervisor) > mdesc_fill_in_cpu_data(cpu_all_mask); > + setup_pagesets(); > } > Index: linux-2.6/arch/x86/kernel/setup_percpu.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/setup_percpu.c 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/arch/x86/kernel/setup_percpu.c 2009-10-01 09:35:39.000000000 -0500 > @@ -269,4 +269,6 @@ void __init setup_per_cpu_areas(void) > > /* Setup cpu initialized, callin, callout masks */ > setup_cpu_local_masks(); > + > + setup_pagesets(); > } > Index: linux-2.6/mm/percpu.c > =================================================================== > --- linux-2.6.orig/mm/percpu.c 2009-10-01 08:54:19.000000000 -0500 > +++ linux-2.6/mm/percpu.c 2009-10-01 09:35:39.000000000 -0500 > @@ -2062,5 +2062,7 @@ void __init setup_per_cpu_areas(void) > delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; > for_each_possible_cpu(cpu) > __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu]; > + > + setup_pagesets(); > } > #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */ > > -- > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab
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