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authorRoland Dreier <rolandd@cisco.com>2008-07-22 14:19:40 -0700
committerRoland Dreier <rolandd@cisco.com>2008-07-22 14:19:40 -0700
commite4044cfc493338cd09870bd45dc646336bb66e9f (patch)
tree2385c18ee6a79393b4e1c5c25ee1f0f980d7da93 /drivers/net
parent899698dad72340b562478b8b770317f2f0fe0c09 (diff)
mlx4_core: Keep free count for MTT buddy allocator
MTT entries are allocated with a buddy allocator, which just keeps bitmaps for each level of the buddy table. However, all free space starts out at the highest order, and small allocations start scanning from the lowest order. When the lowest order tables have no free space, this can lead to scanning potentially millions of bits before finding a free entry at a higher order. We can avoid this by just keeping a count of how many free entries each order has, and skipping the bitmap scan when an order is completely empty. This provides a nice performance boost for a negligible increase in memory usage. Signed-off-by: Roland Dreier <rolandd@cisco.com>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/mlx4/mlx4.h1
-rw-r--r--drivers/net/mlx4/mr.c26
2 files changed, 19 insertions, 8 deletions
diff --git a/drivers/net/mlx4/mlx4.h b/drivers/net/mlx4/mlx4.h
index a4023c2dd05..78038499cff 100644
--- a/drivers/net/mlx4/mlx4.h
+++ b/drivers/net/mlx4/mlx4.h
@@ -118,6 +118,7 @@ struct mlx4_bitmap {
struct mlx4_buddy {
unsigned long **bits;
+ unsigned int *num_free;
int max_order;
spinlock_t lock;
};
diff --git a/drivers/net/mlx4/mr.c b/drivers/net/mlx4/mr.c
index 03a9abcce52..b3ea93b9868 100644
--- a/drivers/net/mlx4/mr.c
+++ b/drivers/net/mlx4/mr.c
@@ -79,23 +79,26 @@ static u32 mlx4_buddy_alloc(struct mlx4_buddy *buddy, int order)
spin_lock(&buddy->lock);
- for (o = order; o <= buddy->max_order; ++o) {
- m = 1 << (buddy->max_order - o);
- seg = find_first_bit(buddy->bits[o], m);
- if (seg < m)
- goto found;
- }
+ for (o = order; o <= buddy->max_order; ++o)
+ if (buddy->num_free[o]) {
+ m = 1 << (buddy->max_order - o);
+ seg = find_first_bit(buddy->bits[o], m);
+ if (seg < m)
+ goto found;
+ }
spin_unlock(&buddy->lock);
return -1;
found:
clear_bit(seg, buddy->bits[o]);
+ --buddy->num_free[o];
while (o > order) {
--o;
seg <<= 1;
set_bit(seg ^ 1, buddy->bits[o]);
+ ++buddy->num_free[o];
}
spin_unlock(&buddy->lock);
@@ -113,11 +116,13 @@ static void mlx4_buddy_free(struct mlx4_buddy *buddy, u32 seg, int order)
while (test_bit(seg ^ 1, buddy->bits[order])) {
clear_bit(seg ^ 1, buddy->bits[order]);
+ --buddy->num_free[order];
seg >>= 1;
++order;
}
set_bit(seg, buddy->bits[order]);
+ ++buddy->num_free[order];
spin_unlock(&buddy->lock);
}
@@ -131,7 +136,9 @@ static int mlx4_buddy_init(struct mlx4_buddy *buddy, int max_order)
buddy->bits = kzalloc((buddy->max_order + 1) * sizeof (long *),
GFP_KERNEL);
- if (!buddy->bits)
+ buddy->num_free = kzalloc((buddy->max_order + 1) * sizeof (int *),
+ GFP_KERNEL);
+ if (!buddy->bits || !buddy->num_free)
goto err_out;
for (i = 0; i <= buddy->max_order; ++i) {
@@ -143,6 +150,7 @@ static int mlx4_buddy_init(struct mlx4_buddy *buddy, int max_order)
}
set_bit(0, buddy->bits[buddy->max_order]);
+ buddy->num_free[buddy->max_order] = 1;
return 0;
@@ -150,9 +158,10 @@ err_out_free:
for (i = 0; i <= buddy->max_order; ++i)
kfree(buddy->bits[i]);
+err_out:
kfree(buddy->bits);
+ kfree(buddy->num_free);
-err_out:
return -ENOMEM;
}
@@ -164,6 +173,7 @@ static void mlx4_buddy_cleanup(struct mlx4_buddy *buddy)
kfree(buddy->bits[i]);
kfree(buddy->bits);
+ kfree(buddy->num_free);
}
static u32 mlx4_alloc_mtt_range(struct mlx4_dev *dev, int order)