Re: [GIT PULL] scheduler fixes

Yinghai Lu
2009-05-24T18:35:11Z

Pekka J Enberg wrote:
> On Mon, 18 May 2009, Linus Torvalds wrote:
>>>> I hate that stupid bootmem allocator. I suspect we seriously
>>>> over-use it, and that we _should_ be able to do the SL*B init
>>>> earlier.
>>> Hm, tempting thought - not sure how to pull it off though.
>> As far as I can recall, one of the things that historically made us want
>> to use the bootmem allocator even relatively late was that the real SLAB
>> allocator had to wait until all the node information etc was initialized.
>>
>> That's pretty damn late. And I wonder if SLUB (and SLOB) might not need a
>> lot less initialization, and work much earlier. Something like that might
>> be the final nail in the coffin for SLAB, and convince me to just say
>> 'we don't support it any more".
>
> Ingo, here's a patch that boots UMA+SMP+SLUB x86-64 kernel on qemu all
> the way to userspace. It probably breaks bunch of things for now but
> something for you to play with if you want.
>

updated with tip/master. also add change to cpupri_init
otherwise will get
[ 0.000000] Memory: 523096612k/537526272k available (10461k kernel code, 656156k absent, 13773504k reserved, 7186k data, 2548k init)
[ 0.000000] SLUB: Genslabs=14, HWalign=64, Order=0-3, MinObjects=0, CPUs=32, Nodes=8
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] WARNING: at kernel/lockdep.c:2282 lockdep_trace_alloc+0xaf/0xee()
[ 0.000000] Hardware name: Sun Fire X4600 M2
[ 0.000000] Modules linked in:
[ 0.000000] Pid: 0, comm: swapper Not tainted 2.6.30-rc6-tip-01778-g0afdd0f-dirty #259
[ 0.000000] Call Trace:
[ 0.000000] [<ffffffff810a0274>] ? lockdep_trace_alloc+0xaf/0xee
[ 0.000000] [<ffffffff81075ab0>] warn_slowpath_common+0x88/0xcb
[ 0.000000] [<ffffffff81075b15>] warn_slowpath_null+0x22/0x38
[ 0.000000] [<ffffffff810a0274>] lockdep_trace_alloc+0xaf/0xee
[ 0.000000] [<ffffffff8110301b>] kmem_cache_alloc_node+0x38/0x14d
[ 0.000000] [<ffffffff813ec548>] ? alloc_cpumask_var_node+0x4a/0x10a
[ 0.000000] [<ffffffff8109eb61>] ? lockdep_init_map+0xb9/0x564
[ 0.000000] [<ffffffff813ec548>] alloc_cpumask_var_node+0x4a/0x10a
[ 0.000000] [<ffffffff813ec62c>] alloc_cpumask_var+0x24/0x3a
[ 0.000000] [<ffffffff819e6306>] cpupri_init+0x7f/0x112
[ 0.000000] [<ffffffff819e5a30>] init_rootdomain+0x72/0xb7
[ 0.000000] [<ffffffff821facce>] sched_init+0x109/0x660
[ 0.000000] [<ffffffff82203082>] ? kmem_cache_init+0x193/0x1b2
[ 0.000000] [<ffffffff821dfd7a>] start_kernel+0x218/0x3f3
[ 0.000000] [<ffffffff821df2a9>] x86_64_start_reservations+0xb9/0xd4
[ 0.000000] [<ffffffff821df3b2>] x86_64_start_kernel+0xee/0x109
[ 0.000000] ---[ end trace a7919e7f17c0a725 ]---

works with 8 sockets numa amd64 box.

YH

---
init/main.c | 28 ++++++++++++++++------------
kernel/irq/handle.c | 23 ++++++++---------------
kernel/sched.c | 34 +++++++++++++---------------------
kernel/sched_cpupri.c | 9 ++++++---
mm/slub.c | 17 ++++++++++-------
5 files changed, 53 insertions(+), 58 deletions(-)

Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c
+++ linux-2.6/init/main.c
@@ -576,6 +576,22 @@ asmlinkage void __init start_kernel(void
setup_nr_cpu_ids();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */

+ build_all_zonelists();
+ page_alloc_init();
+
+ printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
+ parse_early_param();
+ parse_args("Booting kernel", static_command_line, __start___param,
+ __stop___param - __start___param,
+ &unknown_bootoption);
+ /*
+ * Setup kernel memory allocators
+ */
+ pidhash_init();
+ vmalloc_init();
+ vfs_caches_init_early();
+ mem_init();
+ kmem_cache_init();
/*
* Set up the scheduler prior starting any interrupts (such as the
* timer interrupt). Full topology setup happens at smp_init()
@@ -587,13 +603,6 @@ asmlinkage void __init start_kernel(void
* fragile until we cpu_idle() for the first time.
*/
preempt_disable();
- build_all_zonelists();
- page_alloc_init();
- printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
- parse_early_param();
- parse_args("Booting kernel", static_command_line, __start___param,
- __stop___param - __start___param,
- &unknown_bootoption);
if (!irqs_disabled()) {
printk(KERN_WARNING "start_kernel(): bug: interrupts were "
"enabled *very* early, fixing it\n");
@@ -605,7 +614,6 @@ asmlinkage void __init start_kernel(void
/* init some links before init_ISA_irqs() */
early_irq_init();
init_IRQ();
- pidhash_init();
init_timers();
hrtimers_init();
softirq_init();
@@ -647,14 +655,10 @@ asmlinkage void __init start_kernel(void
initrd_start = 0;
}
#endif
- vmalloc_init();
- vfs_caches_init_early();
cpuset_init_early();
page_cgroup_init();
- mem_init();
enable_debug_pagealloc();
cpu_hotplug_init();
- kmem_cache_init();
kmemtrace_init();
debug_objects_mem_init();
idr_init_cache();
Index: linux-2.6/kernel/irq/handle.c
===================================================================
--- linux-2.6.orig/kernel/irq/handle.c
+++ linux-2.6/kernel/irq/handle.c
@@ -18,7 +18,7 @@
#include <linux/kernel_stat.h>
#include <linux/rculist.h>
#include <linux/hash.h>
-#include <linux/bootmem.h>
+#include <linux/slab.h>
#include <trace/events/irq.h>

#include "internals.h"
@@ -45,7 +45,7 @@ void handle_bad_irq(unsigned int irq, st
#if defined(CONFIG_SMP) && defined(CONFIG_GENERIC_HARDIRQS)
static void __init init_irq_default_affinity(void)
{
- alloc_bootmem_cpumask_var(&irq_default_affinity);
+ alloc_cpumask_var(&irq_default_affinity, GFP_NOWAIT);
cpumask_setall(irq_default_affinity);
}
#else
@@ -86,12 +86,8 @@ void __ref init_kstat_irqs(struct irq_de
{
void *ptr;

- if (slab_is_available())
- ptr = kzalloc_node(nr * sizeof(*desc->kstat_irqs),
- GFP_ATOMIC, node);
- else
- ptr = alloc_bootmem_node(NODE_DATA(node),
- nr * sizeof(*desc->kstat_irqs));
+ ptr = kzalloc_node(nr * sizeof(*desc->kstat_irqs),
+ GFP_ATOMIC, node);

/*
* don't overwite if can not get new one
@@ -162,12 +158,12 @@ int __init early_irq_init(void)
legacy_count = ARRAY_SIZE(irq_desc_legacy);

/* allocate irq_desc_ptrs array based on nr_irqs */
- irq_desc_ptrs = alloc_bootmem(nr_irqs * sizeof(void *));
+ irq_desc_ptrs = kcalloc(nr_irqs, sizeof(void *), GFP_NOWAIT);

/* allocate based on nr_cpu_ids */
/* FIXME: invert kstat_irgs, and it'd be a per_cpu_alloc'd thing */
- kstat_irqs_legacy = alloc_bootmem(NR_IRQS_LEGACY * nr_cpu_ids *
- sizeof(int));
+ kstat_irqs_legacy = kzalloc(NR_IRQS_LEGACY * nr_cpu_ids *
+ sizeof(int), GFP_NOWAIT);

for (i = 0; i < legacy_count; i++) {
desc[i].irq = i;
@@ -214,10 +210,7 @@ struct irq_desc * __ref irq_to_desc_allo
if (desc)
goto out_unlock;

- if (slab_is_available())
- desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
- else
- desc = alloc_bootmem_node(NODE_DATA(node), sizeof(*desc));
+ desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);

printk(KERN_DEBUG " alloc irq_desc for %d on node %d\n", irq, node);
if (!desc) {
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -69,7 +69,6 @@
#include <linux/pagemap.h>
#include <linux/hrtimer.h>
#include <linux/tick.h>
-#include <linux/bootmem.h>
#include <linux/debugfs.h>
#include <linux/ctype.h>
#include <linux/ftrace.h>
@@ -7821,24 +7820,21 @@ static void rq_attach_root(struct rq *rq

static int __init_refok init_rootdomain(struct root_domain *rd, bool bootmem)
{
+ gfp_t gfp = GFP_KERNEL;
+
memset(rd, 0, sizeof(*rd));

- if (bootmem) {
- alloc_bootmem_cpumask_var(&def_root_domain.span);
- alloc_bootmem_cpumask_var(&def_root_domain.online);
- alloc_bootmem_cpumask_var(&def_root_domain.rto_mask);
- cpupri_init(&rd->cpupri, true);
- return 0;
- }
+ if (bootmem)
+ gfp = GFP_NOWAIT;

- if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
+ if (!alloc_cpumask_var(&rd->span, gfp))
goto out;
- if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
+ if (!alloc_cpumask_var(&rd->online, gfp))
goto free_span;
- if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
+ if (!alloc_cpumask_var(&rd->rto_mask, gfp))
goto free_online;

- if (cpupri_init(&rd->cpupri, false) != 0)
+ if (cpupri_init(&rd->cpupri, bootmem) != 0)
goto free_rto_mask;
return 0;

@@ -9157,12 +9153,8 @@ void __init sched_init(void)
#ifdef CONFIG_CPUMASK_OFFSTACK
alloc_size += num_possible_cpus() * cpumask_size();
#endif
- /*
- * As sched_init() is called before page_alloc is setup,
- * we use alloc_bootmem().
- */
if (alloc_size) {
- ptr = (unsigned long)alloc_bootmem(alloc_size);
+ ptr = (unsigned long) kzalloc(alloc_size, GFP_NOWAIT);

#ifdef CONFIG_FAIR_GROUP_SCHED
init_task_group.se = (struct sched_entity **)ptr;
@@ -9353,13 +9345,13 @@ void __init sched_init(void)
current->sched_class = &fair_sched_class;

/* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
- alloc_bootmem_cpumask_var(&nohz_cpu_mask);
+ alloc_cpumask_var(&nohz_cpu_mask, GFP_NOWAIT);
#ifdef CONFIG_SMP
#ifdef CONFIG_NO_HZ
- alloc_bootmem_cpumask_var(&nohz.cpu_mask);
- alloc_bootmem_cpumask_var(&nohz.ilb_grp_nohz_mask);
+ alloc_cpumask_var(&nohz.cpu_mask, GFP_NOWAIT);
+ alloc_cpumask_var(&nohz.ilb_grp_nohz_mask, GFP_NOWAIT);
#endif
- alloc_bootmem_cpumask_var(&cpu_isolated_map);
+ alloc_cpumask_var(&cpu_isolated_map, GFP_NOWAIT);
#endif /* SMP */

perf_counter_init();
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -2582,13 +2582,16 @@ static struct kmem_cache *create_kmalloc
if (gfp_flags & SLUB_DMA)
flags = SLAB_CACHE_DMA;

- down_write(&slub_lock);
+ /*
+ * This function is called with IRQs disabled during early-boot on
+ * single CPU so there's no need to take slub_lock here.
+ */
if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
flags, NULL))
goto panic;

list_add(&s->list, &slab_caches);
- up_write(&slub_lock);
+
if (sysfs_slab_add(s))
goto panic;
return s;
@@ -3048,7 +3051,7 @@ void __init kmem_cache_init(void)
* kmem_cache_open for slab_state == DOWN.
*/
create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
- sizeof(struct kmem_cache_node), GFP_KERNEL);
+ sizeof(struct kmem_cache_node), GFP_NOWAIT);
kmalloc_caches[0].refcount = -1;
caches++;

@@ -3061,16 +3064,16 @@ void __init kmem_cache_init(void)
/* Caches that are not of the two-to-the-power-of size */
if (KMALLOC_MIN_SIZE <= 64) {
create_kmalloc_cache(&kmalloc_caches[1],
- "kmalloc-96", 96, GFP_KERNEL);
+ "kmalloc-96", 96, GFP_NOWAIT);
caches++;
create_kmalloc_cache(&kmalloc_caches[2],
- "kmalloc-192", 192, GFP_KERNEL);
+ "kmalloc-192", 192, GFP_NOWAIT);
caches++;
}

for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
create_kmalloc_cache(&kmalloc_caches[i],
- "kmalloc", 1 << i, GFP_KERNEL);
+ "kmalloc", 1 << i, GFP_NOWAIT);
caches++;
}

@@ -3107,7 +3110,7 @@ void __init kmem_cache_init(void)
/* Provide the correct kmalloc names now that the caches are up */
for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++)
kmalloc_caches[i]. name =
- kasprintf(GFP_KERNEL, "kmalloc-%d", 1 << i);
+ kasprintf(GFP_NOWAIT, "kmalloc-%d", 1 << i);

#ifdef CONFIG_SMP
register_cpu_notifier(&slab_notifier);
Index: linux-2.6/kernel/sched_cpupri.c
===================================================================
--- linux-2.6.orig/kernel/sched_cpupri.c
+++ linux-2.6/kernel/sched_cpupri.c
@@ -156,16 +156,19 @@ int __init_refok cpupri_init(struct cpup
{
int i;

+ gfp_t gfp = GFP_KERNEL;
+
memset(cp, 0, sizeof(*cp));

+ if (bootmem)
+ gfp = GFP_NOWAIT;
+
for (i = 0; i < CPUPRI_NR_PRIORITIES; i++) {
struct cpupri_vec *vec = &cp->pri_to_cpu[i];

spin_lock_init(&vec->lock);
vec->count = 0;
- if (bootmem)
- alloc_bootmem_cpumask_var(&vec->mask);
- else if (!alloc_cpumask_var(&vec->mask, GFP_KERNEL))
+ if (!alloc_cpumask_var(&vec->mask, gfp))
goto cleanup;
}