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Message-Id: <20190822171730.781081830@linuxfoundation.org>
Date: Thu, 22 Aug 2019 10:19:46 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Kristian Evensen <kristian.evensen@...il.com>,
Florian Westphal <fw@...len.de>,
Steffen Klassert <steffen.klassert@...unet.com>
Subject: [PATCH 4.14 71/71] xfrm: policy: remove pcpu policy cache
From: Florian Westphal <fw@...len.de>
commit e4db5b61c572475bbbcf63e3c8a2606bfccf2c9d upstream.
Kristian Evensen says:
In a project I am involved in, we are running ipsec (Strongswan) on
different mt7621-based routers. Each router is configured as an
initiator and has around ~30 tunnels to different responders (running
on misc. devices). Before the flow cache was removed (kernel 4.9), we
got a combined throughput of around 70Mbit/s for all tunnels on one
router. However, we recently switched to kernel 4.14 (4.14.48), and
the total throughput is somewhere around 57Mbit/s (best-case). I.e., a
drop of around 20%. Reverting the flow cache removal restores, as
expected, performance levels to that of kernel 4.9.
When pcpu xdst exists, it has to be validated first before it can be
used.
A negative hit thus increases cost vs. no-cache.
As number of tunnels increases, hit rate decreases so this pcpu caching
isn't a viable strategy.
Furthermore, the xdst cache also needs to run with BH off, so when
removing this the bh disable/enable pairs can be removed too.
Kristian tested a 4.14.y backport of this change and reported
increased performance:
In our tests, the throughput reduction has been reduced from around -20%
to -5%. We also see that the overall throughput is independent of the
number of tunnels, while before the throughput was reduced as the number
of tunnels increased.
Reported-by: Kristian Evensen <kristian.evensen@...il.com>
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
include/net/xfrm.h | 1
net/xfrm/xfrm_device.c | 10 ---
net/xfrm/xfrm_policy.c | 138 -------------------------------------------------
net/xfrm/xfrm_state.c | 5 -
4 files changed, 3 insertions(+), 151 deletions(-)
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -323,7 +323,6 @@ int xfrm_policy_register_afinfo(const st
void xfrm_policy_unregister_afinfo(const struct xfrm_policy_afinfo *afinfo);
void km_policy_notify(struct xfrm_policy *xp, int dir,
const struct km_event *c);
-void xfrm_policy_cache_flush(void);
void km_state_notify(struct xfrm_state *x, const struct km_event *c);
struct xfrm_tmpl;
--- a/net/xfrm/xfrm_device.c
+++ b/net/xfrm/xfrm_device.c
@@ -153,12 +153,6 @@ static int xfrm_dev_register(struct net_
return NOTIFY_DONE;
}
-static int xfrm_dev_unregister(struct net_device *dev)
-{
- xfrm_policy_cache_flush();
- return NOTIFY_DONE;
-}
-
static int xfrm_dev_feat_change(struct net_device *dev)
{
if ((dev->features & NETIF_F_HW_ESP) && !dev->xfrmdev_ops)
@@ -178,7 +172,6 @@ static int xfrm_dev_down(struct net_devi
if (dev->features & NETIF_F_HW_ESP)
xfrm_dev_state_flush(dev_net(dev), dev, true);
- xfrm_policy_cache_flush();
return NOTIFY_DONE;
}
@@ -190,9 +183,6 @@ static int xfrm_dev_event(struct notifie
case NETDEV_REGISTER:
return xfrm_dev_register(dev);
- case NETDEV_UNREGISTER:
- return xfrm_dev_unregister(dev);
-
case NETDEV_FEAT_CHANGE:
return xfrm_dev_feat_change(dev);
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -45,8 +45,6 @@ struct xfrm_flo {
u8 flags;
};
-static DEFINE_PER_CPU(struct xfrm_dst *, xfrm_last_dst);
-static struct work_struct *xfrm_pcpu_work __read_mostly;
static DEFINE_SPINLOCK(xfrm_policy_afinfo_lock);
static struct xfrm_policy_afinfo const __rcu *xfrm_policy_afinfo[AF_INET6 + 1]
__read_mostly;
@@ -1715,108 +1713,6 @@ static int xfrm_expand_policies(const st
}
-static void xfrm_last_dst_update(struct xfrm_dst *xdst, struct xfrm_dst *old)
-{
- this_cpu_write(xfrm_last_dst, xdst);
- if (old)
- dst_release(&old->u.dst);
-}
-
-static void __xfrm_pcpu_work_fn(void)
-{
- struct xfrm_dst *old;
-
- old = this_cpu_read(xfrm_last_dst);
- if (old && !xfrm_bundle_ok(old))
- xfrm_last_dst_update(NULL, old);
-}
-
-static void xfrm_pcpu_work_fn(struct work_struct *work)
-{
- local_bh_disable();
- rcu_read_lock();
- __xfrm_pcpu_work_fn();
- rcu_read_unlock();
- local_bh_enable();
-}
-
-void xfrm_policy_cache_flush(void)
-{
- struct xfrm_dst *old;
- bool found = 0;
- int cpu;
-
- might_sleep();
-
- local_bh_disable();
- rcu_read_lock();
- for_each_possible_cpu(cpu) {
- old = per_cpu(xfrm_last_dst, cpu);
- if (old && !xfrm_bundle_ok(old)) {
- if (smp_processor_id() == cpu) {
- __xfrm_pcpu_work_fn();
- continue;
- }
- found = true;
- break;
- }
- }
-
- rcu_read_unlock();
- local_bh_enable();
-
- if (!found)
- return;
-
- get_online_cpus();
-
- for_each_possible_cpu(cpu) {
- bool bundle_release;
-
- rcu_read_lock();
- old = per_cpu(xfrm_last_dst, cpu);
- bundle_release = old && !xfrm_bundle_ok(old);
- rcu_read_unlock();
-
- if (!bundle_release)
- continue;
-
- if (cpu_online(cpu)) {
- schedule_work_on(cpu, &xfrm_pcpu_work[cpu]);
- continue;
- }
-
- rcu_read_lock();
- old = per_cpu(xfrm_last_dst, cpu);
- if (old && !xfrm_bundle_ok(old)) {
- per_cpu(xfrm_last_dst, cpu) = NULL;
- dst_release(&old->u.dst);
- }
- rcu_read_unlock();
- }
-
- put_online_cpus();
-}
-
-static bool xfrm_xdst_can_reuse(struct xfrm_dst *xdst,
- struct xfrm_state * const xfrm[],
- int num)
-{
- const struct dst_entry *dst = &xdst->u.dst;
- int i;
-
- if (xdst->num_xfrms != num)
- return false;
-
- for (i = 0; i < num; i++) {
- if (!dst || dst->xfrm != xfrm[i])
- return false;
- dst = dst->child;
- }
-
- return xfrm_bundle_ok(xdst);
-}
-
static struct xfrm_dst *
xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols,
const struct flowi *fl, u16 family,
@@ -1824,7 +1720,7 @@ xfrm_resolve_and_create_bundle(struct xf
{
struct net *net = xp_net(pols[0]);
struct xfrm_state *xfrm[XFRM_MAX_DEPTH];
- struct xfrm_dst *xdst, *old;
+ struct xfrm_dst *xdst;
struct dst_entry *dst;
int err;
@@ -1839,21 +1735,6 @@ xfrm_resolve_and_create_bundle(struct xf
return ERR_PTR(err);
}
- xdst = this_cpu_read(xfrm_last_dst);
- if (xdst &&
- xdst->u.dst.dev == dst_orig->dev &&
- xdst->num_pols == num_pols &&
- memcmp(xdst->pols, pols,
- sizeof(struct xfrm_policy *) * num_pols) == 0 &&
- xfrm_xdst_can_reuse(xdst, xfrm, err)) {
- dst_hold(&xdst->u.dst);
- while (err > 0)
- xfrm_state_put(xfrm[--err]);
- return xdst;
- }
-
- old = xdst;
-
dst = xfrm_bundle_create(pols[0], xfrm, err, fl, dst_orig);
if (IS_ERR(dst)) {
XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTBUNDLEGENERROR);
@@ -1866,9 +1747,6 @@ xfrm_resolve_and_create_bundle(struct xf
memcpy(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols);
xdst->policy_genid = atomic_read(&pols[0]->genid);
- atomic_set(&xdst->u.dst.__refcnt, 2);
- xfrm_last_dst_update(xdst, old);
-
return xdst;
}
@@ -2069,11 +1947,8 @@ xfrm_bundle_lookup(struct net *net, cons
if (num_xfrms <= 0)
goto make_dummy_bundle;
- local_bh_disable();
xdst = xfrm_resolve_and_create_bundle(pols, num_pols, fl, family,
xflo->dst_orig);
- local_bh_enable();
-
if (IS_ERR(xdst)) {
err = PTR_ERR(xdst);
if (err != -EAGAIN)
@@ -2160,11 +2035,9 @@ struct dst_entry *xfrm_lookup(struct net
goto no_transform;
}
- local_bh_disable();
xdst = xfrm_resolve_and_create_bundle(
pols, num_pols, fl,
family, dst_orig);
- local_bh_enable();
if (IS_ERR(xdst)) {
xfrm_pols_put(pols, num_pols);
@@ -2992,15 +2865,6 @@ static struct pernet_operations __net_in
void __init xfrm_init(void)
{
- int i;
-
- xfrm_pcpu_work = kmalloc_array(NR_CPUS, sizeof(*xfrm_pcpu_work),
- GFP_KERNEL);
- BUG_ON(!xfrm_pcpu_work);
-
- for (i = 0; i < NR_CPUS; i++)
- INIT_WORK(&xfrm_pcpu_work[i], xfrm_pcpu_work_fn);
-
register_pernet_subsys(&xfrm_net_ops);
seqcount_init(&xfrm_policy_hash_generation);
xfrm_input_init();
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -735,10 +735,9 @@ restart:
}
out:
spin_unlock_bh(&net->xfrm.xfrm_state_lock);
- if (cnt) {
+ if (cnt)
err = 0;
- xfrm_policy_cache_flush();
- }
+
return err;
}
EXPORT_SYMBOL(xfrm_state_flush);
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