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Message-ID: <CAMDZJNXPU0mqWabVfQJb2nczcOX8T8i-5n=VrVs4TnDHghOTyw@mail.gmail.com>
Date: Thu, 30 Jul 2020 21:25:17 +0800
From: Tonghao Zhang <xiangxia.m.yue@...il.com>
To: Eelco Chaudron <echaudro@...hat.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>,
ovs dev <dev@...nvswitch.org>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Pravin Shelar <pshelar@....org>,
Florian Westphal <fw@...len.de>
Subject: Re: [PATCH net-next v3 2/2] net: openvswitch: make masks cache size configurable
On Thu, Jul 30, 2020 at 8:33 PM Eelco Chaudron <echaudro@...hat.com> wrote:
>
> Thanks Tonghao for the review, see comments inline below!
>
> If I get no more reviews by the end of the week I’ll send out a v4.
>
> //Eelco
>
>
> On 30 Jul 2020, at 7:07, Tonghao Zhang wrote:
>
> > On Wed, Jul 29, 2020 at 9:27 PM Eelco Chaudron <echaudro@...hat.com>
> > wrote:
> >>
> >> This patch makes the masks cache size configurable, or with
> >> a size of 0, disable it.
> >>
> >> Reviewed-by: Paolo Abeni <pabeni@...hat.com>
> >> Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
> >> ---
> >> Changes in v3:
> >> - Use is_power_of_2() function
> >> - Use array_size() function
> >> - Fix remaining sparse errors
> >>
> >> Changes in v2:
> >> - Fix sparse warnings
> >> - Fix netlink policy items reported by Florian Westphal
> >>
> >> include/uapi/linux/openvswitch.h | 1
> >> net/openvswitch/datapath.c | 14 +++++
> >> net/openvswitch/flow_table.c | 97
> >> +++++++++++++++++++++++++++++++++-----
> >> net/openvswitch/flow_table.h | 10 ++++
> >> 4 files changed, 108 insertions(+), 14 deletions(-)
> >>
> >> diff --git a/include/uapi/linux/openvswitch.h
> >> b/include/uapi/linux/openvswitch.h
> >> index 7cb76e5ca7cf..8300cc29dec8 100644
> >> --- a/include/uapi/linux/openvswitch.h
> >> +++ b/include/uapi/linux/openvswitch.h
> >> @@ -86,6 +86,7 @@ enum ovs_datapath_attr {
> >> OVS_DP_ATTR_MEGAFLOW_STATS, /* struct
> >> ovs_dp_megaflow_stats */
> >> OVS_DP_ATTR_USER_FEATURES, /* OVS_DP_F_* */
> >> OVS_DP_ATTR_PAD,
> >> + OVS_DP_ATTR_MASKS_CACHE_SIZE,
> >> __OVS_DP_ATTR_MAX
> >> };
> >>
> >> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> >> index a54df1fe3ec4..114b2ddb8037 100644
> >> --- a/net/openvswitch/datapath.c
> >> +++ b/net/openvswitch/datapath.c
> >> @@ -1498,6 +1498,7 @@ static size_t ovs_dp_cmd_msg_size(void)
> >> msgsize += nla_total_size_64bit(sizeof(struct ovs_dp_stats));
> >> msgsize += nla_total_size_64bit(sizeof(struct
> >> ovs_dp_megaflow_stats));
> >> msgsize += nla_total_size(sizeof(u32)); /*
> >> OVS_DP_ATTR_USER_FEATURES */
> >> + msgsize += nla_total_size(sizeof(u32)); /*
> >> OVS_DP_ATTR_MASKS_CACHE_SIZE */
> >>
> >> return msgsize;
> >> }
> >> @@ -1535,6 +1536,10 @@ static int ovs_dp_cmd_fill_info(struct
> >> datapath *dp, struct sk_buff *skb,
> >> if (nla_put_u32(skb, OVS_DP_ATTR_USER_FEATURES,
> >> dp->user_features))
> >> goto nla_put_failure;
> >>
> >> + if (nla_put_u32(skb, OVS_DP_ATTR_MASKS_CACHE_SIZE,
> >> + ovs_flow_tbl_masks_cache_size(&dp->table)))
> >> + goto nla_put_failure;
> >> +
> >> genlmsg_end(skb, ovs_header);
> >> return 0;
> >>
> >> @@ -1599,6 +1604,13 @@ static int ovs_dp_change(struct datapath *dp,
> >> struct nlattr *a[])
> >> #endif
> >> }
> >>
> >> + if (a[OVS_DP_ATTR_MASKS_CACHE_SIZE]) {
> >> + u32 cache_size;
> >> +
> >> + cache_size =
> >> nla_get_u32(a[OVS_DP_ATTR_MASKS_CACHE_SIZE]);
> >> + ovs_flow_tbl_masks_cache_resize(&dp->table,
> >> cache_size);
> > Do we should return error code, if we can't change the "mask_cache"
> > size ? for example, -EINVAL, -ENOMEM
>
> Initially, I did not do this due to the fact the new value is reported,
> and on failure, the old value is shown.
> However thinking about it again, it makes more sense to return an error.
> Will sent a v4 with the following to return:
>
> -
> -void ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32
> size)
> +int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size)
> {
> struct mask_cache *mc = rcu_dereference(table->mask_cache);
> struct mask_cache *new;
>
> if (size == mc->cache_size)
> - return;
> + return 0;
> +
> + if (!is_power_of_2(size) && size != 0)
> + return -EINVAL;
add check as below, and we can remove the check in
tbl_mask_cache_alloc function. That
function will only return NULL, if there is no memory. And we can
comment for tbl_mask_cache_alloc, to indicate that size should be a
power of 2.
if ((!is_power_of_2(size) && size != 0) ||
(size * sizeof(struct mask_cache_entry)) > PCPU_MIN_UNIT_SIZE)
Thanks Eelco.
Reviewed-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
> new = tbl_mask_cache_alloc(size);
> if (!new)
> - return;
> + return -ENOMEM;
>
> rcu_assign_pointer(table->mask_cache, new);
> call_rcu(&mc->rcu, mask_cache_rcu_cb);
> +
> + return 0;
> }
>
> >> + }
> >> +
> >> dp->user_features = user_features;
> >>
> >> if (dp->user_features & OVS_DP_F_TC_RECIRC_SHARING)
> >> @@ -1894,6 +1906,8 @@ static const struct nla_policy
> >> datapath_policy[OVS_DP_ATTR_MAX + 1] = {
> >> [OVS_DP_ATTR_NAME] = { .type = NLA_NUL_STRING, .len =
> >> IFNAMSIZ - 1 },
> >> [OVS_DP_ATTR_UPCALL_PID] = { .type = NLA_U32 },
> >> [OVS_DP_ATTR_USER_FEATURES] = { .type = NLA_U32 },
> >> + [OVS_DP_ATTR_MASKS_CACHE_SIZE] = NLA_POLICY_RANGE(NLA_U32,
> >> 0,
> >> + PCPU_MIN_UNIT_SIZE / sizeof(struct
> >> mask_cache_entry)),
> >> };
> >>
> >> static const struct genl_ops dp_datapath_genl_ops[] = {
> >> diff --git a/net/openvswitch/flow_table.c
> >> b/net/openvswitch/flow_table.c
> >> index a5912ea05352..5280aeeef628 100644
> >> --- a/net/openvswitch/flow_table.c
> >> +++ b/net/openvswitch/flow_table.c
> >> @@ -38,8 +38,8 @@
> >> #define MASK_ARRAY_SIZE_MIN 16
> >> #define REHASH_INTERVAL (10 * 60 * HZ)
> >>
> >> +#define MC_DEFAULT_HASH_ENTRIES 256
> >> #define MC_HASH_SHIFT 8
> >> -#define MC_HASH_ENTRIES (1u << MC_HASH_SHIFT)
> >> #define MC_HASH_SEGS ((sizeof(uint32_t) * 8) /
> >> MC_HASH_SHIFT)
> >>
> >> static struct kmem_cache *flow_cache;
> >> @@ -341,15 +341,75 @@ static void flow_mask_remove(struct flow_table
> >> *tbl, struct sw_flow_mask *mask)
> >> }
> >> }
> >>
> >> +static void __mask_cache_destroy(struct mask_cache *mc)
> >> +{
> >> + if (mc->mask_cache)
> >> + free_percpu(mc->mask_cache);
> > free_percpu the NULL is safe. we can remove the "if".
>
> Makes sense, will remove the if() check.
>
> >> + kfree(mc);
> >> +}
> >> +
> >> +static void mask_cache_rcu_cb(struct rcu_head *rcu)
> >> +{
> >> + struct mask_cache *mc = container_of(rcu, struct mask_cache,
> >> rcu);
> >> +
> >> + __mask_cache_destroy(mc);
> >> +}
> >> +
> >> +static struct mask_cache *tbl_mask_cache_alloc(u32 size)
> >> +{
> >> + struct mask_cache_entry __percpu *cache = NULL;
> >> + struct mask_cache *new;
> >> +
> >> + /* Only allow size to be 0, or a power of 2, and does not
> >> exceed
> >> + * percpu allocation size.
> >> + */
> >> + if ((!is_power_of_2(size) && size != 0) ||
> >> + (size * sizeof(struct mask_cache_entry)) >
> >> PCPU_MIN_UNIT_SIZE)
> >> + return NULL;
> >> + new = kzalloc(sizeof(*new), GFP_KERNEL);
> >> + if (!new)
> >> + return NULL;
> >> +
> >> + new->cache_size = size;
> >> + if (new->cache_size > 0) {
> >> + cache = __alloc_percpu(array_size(sizeof(struct
> >> mask_cache_entry),
> >> + new->cache_size),
> >> + __alignof__(struct
> >> mask_cache_entry));
> >> + if (!cache) {
> >> + kfree(new);
> >> + return NULL;
> >> + }
> >> + }
> >> +
> >> + new->mask_cache = cache;
> >> + return new;
> >> +}
> >> +
> >> +void ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32
> >> size)
> >> +{
> >> + struct mask_cache *mc = rcu_dereference(table->mask_cache);
> >> + struct mask_cache *new;
> >> +
> >> + if (size == mc->cache_size)
> >> + return;
> >> +
> >> + new = tbl_mask_cache_alloc(size);
> >> + if (!new)
> >> + return;
> >> +
> >> + rcu_assign_pointer(table->mask_cache, new);
> >> + call_rcu(&mc->rcu, mask_cache_rcu_cb);
> >> +}
> >> +
> >> int ovs_flow_tbl_init(struct flow_table *table)
> >> {
> >> struct table_instance *ti, *ufid_ti;
> >> + struct mask_cache *mc;
> >> struct mask_array *ma;
> >>
> >> - table->mask_cache = __alloc_percpu(sizeof(struct
> >> mask_cache_entry) *
> >> - MC_HASH_ENTRIES,
> >> - __alignof__(struct
> >> mask_cache_entry));
> >> - if (!table->mask_cache)
> >> + mc = tbl_mask_cache_alloc(MC_DEFAULT_HASH_ENTRIES);
> >> + if (!mc)
> >> return -ENOMEM;
> >>
> >> ma = tbl_mask_array_alloc(MASK_ARRAY_SIZE_MIN);
> >> @@ -367,6 +427,7 @@ int ovs_flow_tbl_init(struct flow_table *table)
> >> rcu_assign_pointer(table->ti, ti);
> >> rcu_assign_pointer(table->ufid_ti, ufid_ti);
> >> rcu_assign_pointer(table->mask_array, ma);
> >> + rcu_assign_pointer(table->mask_cache, mc);
> >> table->last_rehash = jiffies;
> >> table->count = 0;
> >> table->ufid_count = 0;
> >> @@ -377,7 +438,7 @@ int ovs_flow_tbl_init(struct flow_table *table)
> >> free_mask_array:
> >> __mask_array_destroy(ma);
> >> free_mask_cache:
> >> - free_percpu(table->mask_cache);
> >> + __mask_cache_destroy(mc);
> >> return -ENOMEM;
> >> }
> >>
> >> @@ -453,9 +514,11 @@ void ovs_flow_tbl_destroy(struct flow_table
> >> *table)
> >> {
> >> struct table_instance *ti = rcu_dereference_raw(table->ti);
> >> struct table_instance *ufid_ti =
> >> rcu_dereference_raw(table->ufid_ti);
> >> + struct mask_cache *mc = rcu_dereference(table->mask_cache);
> >> + struct mask_array *ma =
> >> rcu_dereference_ovsl(table->mask_array);
> >>
> >> - free_percpu(table->mask_cache);
> >> - call_rcu(&table->mask_array->rcu, mask_array_rcu_cb);
> >> + call_rcu(&mc->rcu, mask_cache_rcu_cb);
> >> + call_rcu(&ma->rcu, mask_array_rcu_cb);
> >> table_instance_destroy(table, ti, ufid_ti, false);
> >> }
> >>
> >> @@ -724,6 +787,7 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct
> >> flow_table *tbl,
> >> u32 *n_mask_hit,
> >> u32 *n_cache_hit)
> >> {
> >> + struct mask_cache *mc = rcu_dereference(tbl->mask_cache);
> >> struct mask_array *ma = rcu_dereference(tbl->mask_array);
> >> struct table_instance *ti = rcu_dereference(tbl->ti);
> >> struct mask_cache_entry *entries, *ce;
> >> @@ -733,7 +797,7 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct
> >> flow_table *tbl,
> >>
> >> *n_mask_hit = 0;
> >> *n_cache_hit = 0;
> >> - if (unlikely(!skb_hash)) {
> >> + if (unlikely(!skb_hash || mc->cache_size == 0)) {
> >> u32 mask_index = 0;
> >> u32 cache = 0;
> >>
> >> @@ -749,11 +813,11 @@ struct sw_flow
> >> *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
> >>
> >> ce = NULL;
> >> hash = skb_hash;
> >> - entries = this_cpu_ptr(tbl->mask_cache);
> >> + entries = this_cpu_ptr(mc->mask_cache);
> >>
> >> /* Find the cache entry 'ce' to operate on. */
> >> for (seg = 0; seg < MC_HASH_SEGS; seg++) {
> >> - int index = hash & (MC_HASH_ENTRIES - 1);
> >> + int index = hash & (mc->cache_size - 1);
> >> struct mask_cache_entry *e;
> >>
> >> e = &entries[index];
> >> @@ -867,6 +931,13 @@ int ovs_flow_tbl_num_masks(const struct
> >> flow_table *table)
> >> return READ_ONCE(ma->count);
> >> }
> >>
> >> +u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table)
> >> +{
> >> + struct mask_cache *mc = rcu_dereference(table->mask_cache);
> >> +
> >> + return READ_ONCE(mc->cache_size);
> >> +}
> >> +
> >> static struct table_instance *table_instance_expand(struct
> >> table_instance *ti,
> >> bool ufid)
> >> {
> >> @@ -1095,8 +1166,8 @@ void ovs_flow_masks_rebalance(struct flow_table
> >> *table)
> >> for (i = 0; i < masks_entries; i++) {
> >> int index = masks_and_count[i].index;
> >>
> >> - new->masks[new->count++] =
> >> - rcu_dereference_ovsl(ma->masks[index]);
> >> + if (ovsl_dereference(ma->masks[index]))
> >> + new->masks[new->count++] = ma->masks[index];
> >> }
> >>
> >> rcu_assign_pointer(table->mask_array, new);
> >> diff --git a/net/openvswitch/flow_table.h
> >> b/net/openvswitch/flow_table.h
> >> index 325e939371d8..f2dba952db2f 100644
> >> --- a/net/openvswitch/flow_table.h
> >> +++ b/net/openvswitch/flow_table.h
> >> @@ -27,6 +27,12 @@ struct mask_cache_entry {
> >> u32 mask_index;
> >> };
> >>
> >> +struct mask_cache {
> >> + struct rcu_head rcu;
> >> + u32 cache_size; /* Must be ^2 value. */
> >> + struct mask_cache_entry __percpu *mask_cache;
> >> +};
> >> +
> >> struct mask_count {
> >> int index;
> >> u64 counter;
> >> @@ -53,7 +59,7 @@ struct table_instance {
> >> struct flow_table {
> >> struct table_instance __rcu *ti;
> >> struct table_instance __rcu *ufid_ti;
> >> - struct mask_cache_entry __percpu *mask_cache;
> >> + struct mask_cache __rcu *mask_cache;
> >> struct mask_array __rcu *mask_array;
> >> unsigned long last_rehash;
> >> unsigned int count;
> >> @@ -77,6 +83,8 @@ int ovs_flow_tbl_insert(struct flow_table *table,
> >> struct sw_flow *flow,
> >> const struct sw_flow_mask *mask);
> >> void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow
> >> *flow);
> >> int ovs_flow_tbl_num_masks(const struct flow_table *table);
> >> +u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table);
> >> +void ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32
> >> size);
> >> struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *table,
> >> u32 *bucket, u32 *idx);
> >> struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *,
> >>
> >
> >
> > --
> > Best regards, Tonghao
>
--
Best regards, Tonghao
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