From: Ingo Molnar <mingo@elte.hu>
This patch adds a handful of cond_resched() points to a number of key,
scheduling-latency related non-inlined functions.
This reduces preemption latency for !PREEMPT kernels. These are scheduling
points complementary to PREEMPT_VOLUNTARY scheduling points (might_sleep()
places) - i.e. these are all points where an explicit cond_resched() had
to be added.
Has been tested as part of the -VP patchset.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/fs/exec.c | 1 +
25-akpm/fs/fs-writeback.c | 1 +
25-akpm/fs/select.c | 1 +
25-akpm/kernel/printk.c | 3 +++
25-akpm/mm/memory.c | 1 +
25-akpm/mm/slab.c | 2 +-
25-akpm/mm/vmscan.c | 3 +++
7 files changed, 11 insertions(+), 1 deletion(-)
diff -puN fs/exec.c~sched-fix-scheduling-latencies-for-preempt-kernels fs/exec.c
--- 25/fs/exec.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.634083192 -0700
+++ 25-akpm/fs/exec.c 2004-09-24 02:23:31.653080304 -0700
@@ -184,6 +184,7 @@ static int count(char __user * __user *
argv++;
if(++i > max)
return -E2BIG;
+ cond_resched();
}
}
return i;
diff -puN fs/fs-writeback.c~sched-fix-scheduling-latencies-for-preempt-kernels fs/fs-writeback.c
--- 25/fs/fs-writeback.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.635083040 -0700
+++ 25-akpm/fs/fs-writeback.c 2004-09-24 02:23:31.654080152 -0700
@@ -370,6 +370,7 @@ sync_sb_inodes(struct super_block *sb, s
list_move(&inode->i_list, &sb->s_dirty);
}
spin_unlock(&inode_lock);
+ cond_resched();
iput(inode);
spin_lock(&inode_lock);
if (wbc->nr_to_write <= 0)
diff -puN fs/select.c~sched-fix-scheduling-latencies-for-preempt-kernels fs/select.c
--- 25/fs/select.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.639082432 -0700
+++ 25-akpm/fs/select.c 2004-09-24 02:23:31.655080000 -0700
@@ -240,6 +240,7 @@ int do_select(int n, fd_set_bits *fds, l
retval++;
}
}
+ cond_resched();
}
if (res_in)
*rinp = res_in;
diff -puN kernel/printk.c~sched-fix-scheduling-latencies-for-preempt-kernels kernel/printk.c
--- 25/kernel/printk.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.641082128 -0700
+++ 25-akpm/kernel/printk.c 2004-09-24 02:23:31.657079696 -0700
@@ -283,6 +283,7 @@ int do_syslog(int type, char __user * bu
error = __put_user(c,buf);
buf++;
i++;
+ cond_resched();
spin_lock_irq(&logbuf_lock);
}
spin_unlock_irq(&logbuf_lock);
@@ -324,6 +325,7 @@ int do_syslog(int type, char __user * bu
c = LOG_BUF(j);
spin_unlock_irq(&logbuf_lock);
error = __put_user(c,&buf[count-1-i]);
+ cond_resched();
spin_lock_irq(&logbuf_lock);
}
spin_unlock_irq(&logbuf_lock);
@@ -339,6 +341,7 @@ int do_syslog(int type, char __user * bu
error = -EFAULT;
break;
}
+ cond_resched();
}
}
break;
diff -puN mm/memory.c~sched-fix-scheduling-latencies-for-preempt-kernels mm/memory.c
--- 25/mm/memory.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.643081824 -0700
+++ 25-akpm/mm/memory.c 2004-09-24 02:23:31.659079392 -0700
@@ -1526,6 +1526,7 @@ do_no_page(struct mm_struct *mm, struct
}
smp_rmb(); /* Prevent CPU from reordering lock-free ->nopage() */
retry:
+ cond_resched();
new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
/* no page was available -- either SIGBUS or OOM */
diff -puN mm/slab.c~sched-fix-scheduling-latencies-for-preempt-kernels mm/slab.c
--- 25/mm/slab.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.646081368 -0700
+++ 25-akpm/mm/slab.c 2004-09-24 02:23:31.662078936 -0700
@@ -2791,7 +2791,7 @@ static void cache_reap(void *unused)
next_unlock:
spin_unlock_irq(&searchp->spinlock);
next:
- ;
+ cond_resched();
}
check_irq_on();
up(&cache_chain_sem);
diff -puN mm/vmscan.c~sched-fix-scheduling-latencies-for-preempt-kernels mm/vmscan.c
--- 25/mm/vmscan.c~sched-fix-scheduling-latencies-for-preempt-kernels 2004-09-24 02:23:31.648081064 -0700
+++ 25-akpm/mm/vmscan.c 2004-09-24 02:23:31.664078632 -0700
@@ -361,6 +361,8 @@ static int shrink_list(struct list_head
int may_enter_fs;
int referenced;
+ cond_resched();
+
page = lru_to_page(page_list);
list_del(&page->lru);
@@ -710,6 +712,7 @@ refill_inactive_zone(struct zone *zone,
reclaim_mapped = 1;
while (!list_empty(&l_hold)) {
+ cond_resched();
page = lru_to_page(&l_hold);
list_del(&page->lru);
if (page_mapped(page)) {
_