page fault scalability patch V14 [7/7]: Split RSS counters

Christoph Lameter
2005-01-04T19:39:25Z

Changelog
* Split rss counter into the task structure
* remove 3 checks of rss in mm/rmap.c
* increment current->rss instead of mm->rss in the page fault handler
* move incrementing of anon_rss out of page_add_anon_rmap to group
the increments more tightly and allow a better cache utilization

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.10/include/linux/sched.h
=================================--- linux-2.6.10.orig/include/linux/sched.h 2004-12-24 13:33:59.000000000 -0800
+++ linux-2.6.10/include/linux/sched.h 2005-01-03 12:21:32.000000000 -0800
@@ -30,6 +30,7 @@
#include <linux/pid.h>
#include <linux/percpu.h>
#include <linux/topology.h>
+#include <linux/rcupdate.h>

struct exec_domain;

@@ -217,6 +218,7 @@
int map_count; /* number of VMAs */
struct rw_semaphore mmap_sem;
spinlock_t page_table_lock; /* Protects page tables, mm->rss, mm->anon_rss */
+ long rss, anon_rss;

struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung
* together off init_mm.mmlist, and are protected
@@ -226,7 +228,7 @@
unsigned long start_code, end_code, start_data, end_data;
unsigned long start_brk, brk, start_stack;
unsigned long arg_start, arg_end, env_start, env_end;
- unsigned long rss, anon_rss, total_vm, locked_vm, shared_vm;
+ unsigned long total_vm, locked_vm, shared_vm;
unsigned long exec_vm, stack_vm, reserved_vm, def_flags, nr_ptes;

unsigned long saved_auxv[42]; /* for /proc/PID/auxv */
@@ -236,6 +238,7 @@

/* Architecture-specific MM context */
mm_context_t context;
+ struct list_head task_list; /* Tasks using this mm */

/* Token based thrashing protection. */
unsigned long swap_token_time;
@@ -545,6 +548,9 @@
struct list_head ptrace_list;

struct mm_struct *mm, *active_mm;
+ /* Split counters from mm */
+ long rss;
+ long anon_rss;

/* task state */
struct linux_binfmt *binfmt;
@@ -578,6 +584,10 @@
struct completion *vfork_done; /* for vfork() */
int __user *set_child_tid; /* CLONE_CHILD_SETTID */
int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */
+
+ /* List of other tasks using the same mm */
+ struct list_head mm_tasks;
+ struct rcu_head rcu_head; /* For freeing the task via rcu */

unsigned long rt_priority;
unsigned long it_real_value, it_prof_value, it_virt_value;
@@ -1124,6 +1134,12 @@

#endif

+void get_rss(struct mm_struct *mm, unsigned long *rss, unsigned long *anon_rss);
+
+void mm_remove_thread(struct mm_struct *mm, struct task_struct *tsk);
+void mm_add_thread(struct mm_struct *mm, struct task_struct *tsk);
+
#endif /* __KERNEL__ */

#endif
+
Index: linux-2.6.10/fs/proc/task_mmu.c
=================================--- linux-2.6.10.orig/fs/proc/task_mmu.c 2004-12-24 13:34:01.000000000 -0800
+++ linux-2.6.10/fs/proc/task_mmu.c 2005-01-03 12:21:32.000000000 -0800
@@ -6,8 +6,9 @@

char *task_mem(struct mm_struct *mm, char *buffer)
{
- unsigned long data, text, lib;
+ unsigned long data, text, lib, rss, anon_rss;

+ get_rss(mm, &rss, &anon_rss);
data = mm->total_vm - mm->shared_vm - mm->stack_vm;
text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
@@ -22,7 +23,7 @@
"VmPTE:\t%8lu kB\n",
(mm->total_vm - mm->reserved_vm) << (PAGE_SHIFT-10),
mm->locked_vm << (PAGE_SHIFT-10),
- mm->rss << (PAGE_SHIFT-10),
+ rss << (PAGE_SHIFT-10),
data << (PAGE_SHIFT-10),
mm->stack_vm << (PAGE_SHIFT-10), text, lib,
(PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10);
@@ -37,11 +38,14 @@
int task_statm(struct mm_struct *mm, int *shared, int *text,
int *data, int *resident)
{
- *shared = mm->rss - mm->anon_rss;
+ unsigned long rss, anon_rss;
+
+ get_rss(mm, &rss, &anon_rss);
+ *shared = rss - anon_rss;
*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
>> PAGE_SHIFT;
*data = mm->total_vm - mm->shared_vm;
- *resident = mm->rss;
+ *resident = rss;
return mm->total_vm;
}

Index: linux-2.6.10/fs/proc/array.c
=================================--- linux-2.6.10.orig/fs/proc/array.c 2004-12-24 13:35:00.000000000 -0800
+++ linux-2.6.10/fs/proc/array.c 2005-01-03 12:21:32.000000000 -0800
@@ -302,7 +302,7 @@

static int do_task_stat(struct task_struct *task, char * buffer, int whole)
{
- unsigned long vsize, eip, esp, wchan = ~0UL;
+ unsigned long rss, anon_rss, vsize, eip, esp, wchan = ~0UL;
long priority, nice;
int tty_pgrp = -1, tty_nr = 0;
sigset_t sigign, sigcatch;
@@ -325,6 +325,7 @@
vsize = task_vsize(mm);
eip = KSTK_EIP(task);
esp = KSTK_ESP(task);
+ get_rss(mm, &rss, &anon_rss);
}

get_task_comm(tcomm, task);
@@ -420,7 +421,7 @@
jiffies_to_clock_t(task->it_real_value),
start_time,
vsize,
- mm ? mm->rss : 0, /* you might want to shift this left 3 */
+ mm ? rss : 0, /* you might want to shift this left 3 */
rsslim,
mm ? mm->start_code : 0,
mm ? mm->end_code : 0,
Index: linux-2.6.10/mm/rmap.c
=================================--- linux-2.6.10.orig/mm/rmap.c 2005-01-03 10:31:41.000000000 -0800
+++ linux-2.6.10/mm/rmap.c 2005-01-03 12:21:32.000000000 -0800
@@ -264,8 +264,6 @@
pte_t *pte;
int referenced = 0;

- if (!mm->rss)
- goto out;
address = vma_address(page, vma);
if (address = -EFAULT)
goto out;
@@ -446,8 +444,6 @@
BUG_ON(PageReserved(page));
BUG_ON(!anon_vma);

- vma->vm_mm->anon_rss++;
-
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
index = (address - vma->vm_start) >> PAGE_SHIFT;
index += vma->vm_pgoff;
@@ -519,8 +515,6 @@
pte_t pteval;
int ret = SWAP_AGAIN;

- if (!mm->rss)
- goto out;
address = vma_address(page, vma);
if (address = -EFAULT)
goto out;
@@ -817,8 +811,7 @@
if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
continue;
cursor = (unsigned long) vma->vm_private_data;
- while (vma->vm_mm->rss &&
- cursor < max_nl_cursor &&
+ while (cursor < max_nl_cursor &&
cursor < vma->vm_end - vma->vm_start) {
try_to_unmap_cluster(cursor, &mapcount, vma);
cursor += CLUSTER_SIZE;
Index: linux-2.6.10/kernel/fork.c
=================================--- linux-2.6.10.orig/kernel/fork.c 2004-12-24 13:33:59.000000000 -0800
+++ linux-2.6.10/kernel/fork.c 2005-01-03 12:21:32.000000000 -0800
@@ -78,10 +78,16 @@
static kmem_cache_t *task_struct_cachep;
#endif

+static void rcu_free_task(struct rcu_head *head)
+{
+ struct task_struct *tsk = container_of(head ,struct task_struct, rcu_head);
+ free_task_struct(tsk);
+}
+
void free_task(struct task_struct *tsk)
{
free_thread_info(tsk->thread_info);
- free_task_struct(tsk);
+ call_rcu(&tsk->rcu_head, rcu_free_task);
}
EXPORT_SYMBOL(free_task);

@@ -98,7 +104,7 @@
put_group_info(tsk->group_info);

if (!profile_handoff_task(tsk))
- free_task(tsk);
+ call_rcu(&tsk->rcu_head, rcu_free_task);
}

void __init fork_init(unsigned long mempages)
@@ -151,6 +157,7 @@
*tsk = *orig;
tsk->thread_info = ti;
ti->task = tsk;
+ tsk->rss = 0;

/* One for us, one for whoever does the "release_task()" (usually parent) */
atomic_set(&tsk->usage,2);
@@ -292,6 +299,7 @@
atomic_set(&mm->mm_count, 1);
init_rwsem(&mm->mmap_sem);
INIT_LIST_HEAD(&mm->mmlist);
+ INIT_LIST_HEAD(&mm->task_list);
mm->core_waiters = 0;
mm->nr_ptes = 0;
spin_lock_init(&mm->page_table_lock);
@@ -400,6 +408,8 @@

/* Get rid of any cached register state */
deactivate_mm(tsk, mm);
+ if (mm)
+ mm_remove_thread(mm, tsk);

/* notify parent sleeping on vfork() */
if (vfork_done) {
@@ -447,8 +457,8 @@
* new threads start up in user mode using an mm, which
* allows optimizing out ipis; the tlb_gather_mmu code
* is an example.
+ * (mm_add_thread does use the ptl .... )
*/
- spin_unlock_wait(&oldmm->page_table_lock);
goto good_mm;
}

@@ -470,6 +480,7 @@
goto free_pt;

good_mm:
+ mm_add_thread(mm, tsk);
tsk->mm = mm;
tsk->active_mm = mm;
return 0;
@@ -1063,7 +1074,7 @@
atomic_dec(&p->user->processes);
free_uid(p->user);
bad_fork_free:
- free_task(p);
+ call_rcu(&p->rcu_head, rcu_free_task);
goto fork_out;
}

Index: linux-2.6.10/mm/memory.c
=================================--- linux-2.6.10.orig/mm/memory.c 2005-01-03 11:15:55.000000000 -0800
+++ linux-2.6.10/mm/memory.c 2005-01-03 12:21:32.000000000 -0800
@@ -909,6 +909,7 @@
struct page *map;
int lookup_write = write;
while (!(map = follow_page(mm, start, lookup_write))) {
+ unsigned long rss, anon_rss;
/*
* Shortcut for anonymous pages. We don't want
* to force the creation of pages tables for
@@ -921,6 +922,17 @@
map = ZERO_PAGE(start);
break;
}
+ if (mm != current->mm) {
+ /*
+ * handle_mm_fault uses the current pointer
+ * for a split rss counter. The current pointer
+ * is not correct if we are using a different mm
+ */
+ rss = current->rss;
+ anon_rss = current->anon_rss;
+ current->rss = 0;
+ current->anon_rss = 0;
+ }
spin_unlock(&mm->page_table_lock);
switch (handle_mm_fault(mm,vma,start,write)) {
case VM_FAULT_MINOR:
@@ -945,6 +957,12 @@
*/
lookup_write = write && !force;
spin_lock(&mm->page_table_lock);
+ if (mm != current->mm) {
+ mm->rss += current->rss;
+ mm->anon_rss += current->anon_rss;
+ current->rss = rss;
+ current->anon_rss = anon_rss;
+ }
}
if (pages) {
pages[i] = get_page_map(map);
@@ -1325,6 +1343,7 @@
break_cow(vma, new_page, address, page_table);
lru_cache_add_active(new_page);
page_add_anon_rmap(new_page, vma, address);
+ mm->anon_rss++;

/* Free the old page.. */
new_page = old_page;
@@ -1608,6 +1627,7 @@
flush_icache_page(vma, page);
set_pte(page_table, pte);
page_add_anon_rmap(page, vma, address);
+ mm->anon_rss++;

if (write_access) {
if (do_wp_page(mm, vma, address,
@@ -1674,6 +1694,7 @@
page_add_anon_rmap(page, vma, addr);
lru_cache_add_active(page);
mm->rss++;
+ mm->anon_rss++;

}
pte_unmap(page_table);
@@ -1780,6 +1801,7 @@
if (anon) {
lru_cache_add_active(new_page);
page_add_anon_rmap(new_page, vma, address);
+ mm->anon_rss++;
} else
page_add_file_rmap(new_page);
pte_unmap(page_table);
@@ -2143,3 +2165,49 @@
}

#endif
+
+void get_rss(struct mm_struct *mm, unsigned long *rss, unsigned long *anon_rss)
+{
+ struct list_head *y;
+ struct task_struct *t;
+ long rss_sum, anon_rss_sum;
+
+ rcu_read_lock();
+ rss_sum = mm->rss;
+ anon_rss_sum = mm->anon_rss;
+ list_for_each_rcu(y, &mm->task_list) {
+ t = list_entry(y, struct task_struct, mm_tasks);
+ rss_sum += t->rss;
+ anon_rss_sum += t->anon_rss;
+ }
+ if (rss_sum < 0)
+ rss_sum = 0;
+ if (anon_rss_sum < 0)
+ anon_rss_sum = 0;
+ rcu_read_unlock();
+ *rss = rss_sum;
+ *anon_rss = anon_rss_sum;
+}
+
+void mm_remove_thread(struct mm_struct *mm, struct task_struct *tsk)
+{
+ if (!mm)
+ return;
+
+ spin_lock(&mm->page_table_lock);
+ mm->rss += tsk->rss;
+ mm->anon_rss += tsk->anon_rss;
+ list_del_rcu(&tsk->mm_tasks);
+ spin_unlock(&mm->page_table_lock);
+}
+
+void mm_add_thread(struct mm_struct *mm, struct task_struct *tsk)
+{
+ spin_lock(&mm->page_table_lock);
+ tsk->rss = 0;
+ tsk->anon_rss = 0;
+ list_add_rcu(&tsk->mm_tasks, &mm->task_list);
+ spin_unlock(&mm->page_table_lock);
+}
+
+
Index: linux-2.6.10/include/linux/init_task.h
=================================--- linux-2.6.10.orig/include/linux/init_task.h 2004-12-24 13:33:52.000000000 -0800
+++ linux-2.6.10/include/linux/init_task.h 2005-01-03 12:21:32.000000000 -0800
@@ -42,6 +42,7 @@
.mmlist = LIST_HEAD_INIT(name.mmlist), \
.cpu_vm_mask = CPU_MASK_ALL, \
.default_kioctx = INIT_KIOCTX(name.default_kioctx, name), \
+ .task_list = LIST_HEAD_INIT(name.task_list), \
}

#define INIT_SIGNALS(sig) { \
@@ -112,6 +113,7 @@
.proc_lock = SPIN_LOCK_UNLOCKED, \
.switch_lock = SPIN_LOCK_UNLOCKED, \
.journal_info = NULL, \
+ .mm_tasks = LIST_HEAD_INIT(tsk.mm_tasks), \
}

Index: linux-2.6.10/fs/exec.c
=================================--- linux-2.6.10.orig/fs/exec.c 2005-01-03 10:31:31.000000000 -0800
+++ linux-2.6.10/fs/exec.c 2005-01-03 12:21:32.000000000 -0800
@@ -549,6 +549,7 @@
tsk->active_mm = mm;
activate_mm(active_mm, mm);
task_unlock(tsk);
+ mm_add_thread(mm, current);
arch_pick_mmap_layout(mm);
if (old_mm) {
if (active_mm != old_mm) BUG();
Index: linux-2.6.10/fs/aio.c
=================================--- linux-2.6.10.orig/fs/aio.c 2004-12-24 13:34:44.000000000 -0800
+++ linux-2.6.10/fs/aio.c 2005-01-03 12:21:32.000000000 -0800
@@ -577,6 +577,7 @@
tsk->active_mm = mm;
activate_mm(active_mm, mm);
task_unlock(tsk);
+ mm_add_thread(mm, tsk);

mmdrop(active_mm);
}
@@ -596,6 +597,7 @@
{
struct task_struct *tsk = current;

+ mm_remove_thread(mm,tsk);
task_lock(tsk);
tsk->flags &= ~PF_BORROWED_MM;
tsk->mm = NULL;
Index: linux-2.6.10/mm/swapfile.c
=================================--- linux-2.6.10.orig/mm/swapfile.c 2005-01-03 10:31:31.000000000 -0800
+++ linux-2.6.10/mm/swapfile.c 2005-01-03 12:21:32.000000000 -0800
@@ -432,6 +432,7 @@
swp_entry_t entry, struct page *page)
{
vma->vm_mm->rss++;
+ vma->vm_mm->anon_rss++;
get_page(page);
set_pte(dir, pte_mkold(mk_pte(page, vma->vm_page_prot)));
page_add_anon_rmap(page, vma, address);