Subject: Re: Big performance loss from 3.4.63 to 3.10.13 when routing ipv4

From: Steffen Klassert <[email-masked]>
Date: Fri, 25 Oct 2013 11:20:43 +0200

On Fri, Oct 25, 2013 at 01:50:28AM -0700, Eric Dumazet wrote:
> 
> 32768 as the default seems fine to me
> 
> 448 bytes per dst -> thats less than 30 Mbytes of memory if we hit 65536
> dst.
> 

Ok, I'll add the patch below to to the ipsec tree if everyone is fine
with that threshold.

Subject: [PATCH RFC] xfrm: Increase the garbage collector threshold

With the removal of the routing cache, we lost the
option to tweak the garbage collector threshold
along with the maximum routing cache size. So git
commit 703fb94ec ("xfrm: Fix the gc threshold value
for ipv4") moved back to a static threshold.

It turned out that the current threshold before we
start garbage collecting is much to small for some
workloads, so increase it from 1024 to 32768. This
means that we start the garbage collector if we have
more than 32768 dst entries in the system and refuse
new allocations if we are above 65536.

Signed-off-by: Steffen Klassert <[email-masked]>
---
 net/ipv4/xfrm4_policy.c |    2 +-
 net/ipv6/xfrm6_policy.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index ccde542..4764ee4 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -236,7 +236,7 @@ static struct dst_ops xfrm4_dst_ops = {
 	.destroy =		xfrm4_dst_destroy,
 	.ifdown =		xfrm4_dst_ifdown,
 	.local_out =		__ip_local_out,
-	.gc_thresh =		1024,
+	.gc_thresh =		32768,
 };
 
 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 08ed277..dd503a3 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -285,7 +285,7 @@ static struct dst_ops xfrm6_dst_ops = {
 	.destroy =		xfrm6_dst_destroy,
 	.ifdown =		xfrm6_dst_ifdown,
 	.local_out =		__ip6_local_out,
-	.gc_thresh =		1024,
+	.gc_thresh =		32768,
 };
 
 static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
-- 
1.7.9.5