diff mbox series

[net] mlxsw: spectrum_router: Avoid expensive lookup during route removal

Message ID 20171008095326.1238-1-jiri@resnulli.us
State Accepted, archived
Delegated to: David Miller
Headers show
Series [net] mlxsw: spectrum_router: Avoid expensive lookup during route removal | expand

Commit Message

Jiri Pirko Oct. 8, 2017, 9:53 a.m. UTC 
From: Ido Schimmel <idosch@mellanox.com>

In commit fc922bb0dd94 ("mlxsw: spectrum_router: Use one LPM tree for
all virtual routers") I increased the scale of supported VRFs by having
all of them share the same LPM tree.

In order to avoid look-ups for prefix lengths that don't exist, each
route removal would trigger an aggregation across all the active virtual
routers to see which prefix lengths are in use and which aren't and
structure the tree accordingly.

With the way the data structures are currently laid out, this is a very
expensive operation. When preformed repeatedly - due to the invocation
of the abort mechanism - and with enough VRFs, this can result in a hung
task.

For now, avoid this optimization until it can be properly re-added in
net-next.

Fixes: fc922bb0dd94 ("mlxsw: spectrum_router: Use one LPM tree for all virtual routers")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: David Ahern <dsa@cumulusnetworks.com>
Tested-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 14 --------------
 1 file changed, 14 deletions(-)

Comments

David Miller Oct. 8, 2017, 5:06 p.m. UTC | #1 
From: Jiri Pirko <jiri@resnulli.us>
Date: Sun,  8 Oct 2017 11:53:26 +0200

> From: Ido Schimmel <idosch@mellanox.com>
> 
> In commit fc922bb0dd94 ("mlxsw: spectrum_router: Use one LPM tree for
> all virtual routers") I increased the scale of supported VRFs by having
> all of them share the same LPM tree.
> 
> In order to avoid look-ups for prefix lengths that don't exist, each
> route removal would trigger an aggregation across all the active virtual
> routers to see which prefix lengths are in use and which aren't and
> structure the tree accordingly.
> 
> With the way the data structures are currently laid out, this is a very
> expensive operation. When preformed repeatedly - due to the invocation
> of the abort mechanism - and with enough VRFs, this can result in a hung
> task.
> 
> For now, avoid this optimization until it can be properly re-added in
> net-next.
> 
> Fixes: fc922bb0dd94 ("mlxsw: spectrum_router: Use one LPM tree for all virtual routers")
> Signed-off-by: Ido Schimmel <idosch@mellanox.com>
> Reported-by: David Ahern <dsa@cumulusnetworks.com>
> Tested-by: David Ahern <dsa@cumulusnetworks.com>
> Signed-off-by: Jiri Pirko <jiri@mellanox.com>

Applied.
diff mbox series

Patch

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 032089e..c16718d 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -3505,20 +3505,6 @@  static int mlxsw_sp_fib_lpm_tree_link(struct mlxsw_sp *mlxsw_sp,
 static void mlxsw_sp_fib_lpm_tree_unlink(struct mlxsw_sp *mlxsw_sp,
 					 struct mlxsw_sp_fib *fib)
 {
-	struct mlxsw_sp_prefix_usage req_prefix_usage = {{ 0 } };
-	struct mlxsw_sp_lpm_tree *lpm_tree;
-
-	/* Aggregate prefix lengths across all virtual routers to make
-	 * sure we only have used prefix lengths in the LPM tree.
-	 */
-	mlxsw_sp_vrs_prefixes(mlxsw_sp, fib->proto, &req_prefix_usage);
-	lpm_tree = mlxsw_sp_lpm_tree_get(mlxsw_sp, &req_prefix_usage,
-					 fib->proto);
-	if (IS_ERR(lpm_tree))
-		goto err_tree_get;
-	mlxsw_sp_vrs_lpm_tree_replace(mlxsw_sp, fib, lpm_tree);
-
-err_tree_get:
 	if (!mlxsw_sp_prefix_usage_none(&fib->prefix_usage))
 		return;
 	mlxsw_sp_vr_lpm_tree_unbind(mlxsw_sp, fib);