Aneesh Kumar K.V wrote:
Eric Sandeen wrote:
Aneesh Kumar K.V wrote:
Hi,
In block reservation code while rebalancing the free blocks why are
we not looking at the reservation slots that have no free blocks
left. Rebalancing
the free blocks equally across all the reservation slots will make sure
we have less chances of failure later when we try to reserve blocks.
I understand that we consider the CPU slot on which reservation
failed while
rebalancing. But what is preventing considering other CPU slot that
might have
zero blocks left ?
+void ext4_rebalance_reservation(struct ext4_reservation_slot *rs,
__u64 free)
+{
+ int i, used_slots = 0;
+ __u64 chunk;
+
+ /* let's know what slots have been used */
+ for (i = 0; i < NR_CPUS; i++)
BTW... I think you really want:
+ for_each_possible_cpu(i) {
in this and other similar places.
NR_CPUS is a config-time option that may be much more than your actual
count of runtime possible CPUs... on ia64 it's 512 by default, for
example. That's a lot of pointlessness on a 2, 4 or 8 cpu box :)
I can whip up a proper patch for current code to send (again)...
This is what i have modified. I am yet to build test it. I am looking at
forward porting the
mballoc patches and was planning to send it together.
I build tested the patch. I guess we need the below small patch on top of the previous
patch.
-aneesh
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index ad3f57c..df6b83c 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -1981,7 +1981,7 @@ int ext4_reserve_init(struct super_block *sb)
struct ext4_reservation_slot *rs;
int i;
- rs = percpu_alloc(sizeof(struct ext4_reservation_slot), GFP_KERNEL);
+ rs = alloc_percpu(struct ext4_reservation_slot);
if (rs == NULL)
return -ENOMEM;
sbi->s_reservation_slots = rs;
