| Message ID | 1570802447-8019-6-git-send-email-xiangxia.m.yue@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | optimize openvswitch flow looking up | expand |
On Fri, Oct 11, 2019 at 7:05 AM <xiangxia.m.yue@gmail.com> wrote: > > From: Tonghao Zhang <xiangxia.m.yue@gmail.com> > > The full looking up on flow table traverses all mask array. > If mask-array is too large, the number of invalid flow-mask > increase, performance will be drop. > > This patch optimizes mask-array operation: > > * Inserting, insert it [ma->count- 1] directly. > * Removing, only change last and current mask point, and free current mask. > * Looking up, full looking up will break if mask is NULL. > > The function which changes or gets *count* of struct mask_array, > is protected by ovs_lock, but flow_lookup (not protected) should use *max* of > struct mask_array. > > Functions protected by ovs_lock: > * tbl_mask_array_del_mask > * tbl_mask_array_add_mask > * flow_mask_find > * ovs_flow_tbl_lookup_exact > * ovs_flow_tbl_num_masks > > Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com> > --- > net/openvswitch/flow_table.c | 114 ++++++++++++++++++++++--------------------- > 1 file changed, 58 insertions(+), 56 deletions(-) > > diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c > index 4c82960..1b99f8e 100644 > --- a/net/openvswitch/flow_table.c > +++ b/net/openvswitch/flow_table.c > @@ -198,10 +198,8 @@ static int tbl_mask_array_realloc(struct flow_table *tbl, int size) > if (old) { > int i; > > - for (i = 0; i < old->max; i++) { > - if (ovsl_dereference(old->masks[i])) > - new->masks[new->count++] = old->masks[i]; > - } > + for (i = 0; i < old->count; i++) > + new->masks[new->count++] = old->masks[i]; > } > > rcu_assign_pointer(tbl->mask_array, new); > @@ -538,7 +536,7 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl, > > mask = rcu_dereference_ovsl(ma->masks[i]); > if (!mask) > - continue; > + break; > > flow = masked_flow_lookup(ti, key, mask, n_mask_hit); > if (flow) { /* Found */ > @@ -632,15 +630,13 @@ struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl, > int i; > > /* Always called under ovs-mutex. */ > - for (i = 0; i < ma->max; i++) { > + for (i = 0; i < ma->count; i++) { > struct table_instance *ti = rcu_dereference_ovsl(tbl->ti); > u32 __always_unused n_mask_hit; > struct sw_flow_mask *mask; > struct sw_flow *flow; > > mask = ovsl_dereference(ma->masks[i]); > - if (!mask) > - continue; > > flow = masked_flow_lookup(ti, match->key, mask, &n_mask_hit); > if (flow && ovs_identifier_is_key(&flow->id) && > @@ -704,21 +700,34 @@ static struct table_instance *table_instance_expand(struct table_instance *ti, > return table_instance_rehash(ti, ti->n_buckets * 2, ufid); > } > > -static void tbl_mask_array_delete_mask(struct mask_array *ma, > - struct sw_flow_mask *mask) > +static void tbl_mask_array_del_mask(struct flow_table *tbl, > + struct sw_flow_mask *mask) > { > + struct mask_array *ma = ovsl_dereference(tbl->mask_array); > int i; > > /* Remove the deleted mask pointers from the array */ > - for (i = 0; i < ma->max; i++) { > - if (mask == ovsl_dereference(ma->masks[i])) { > - RCU_INIT_POINTER(ma->masks[i], NULL); > - ma->count--; > - kfree_rcu(mask, rcu); > - return; > - } > + for (i = 0; i < ma->count; i++) { > + if (mask == ovsl_dereference(ma->masks[i])) > + goto found; > } > + > BUG(); > + return; > + > +found: > + ma->count--; > + smp_wmb(); > + You need corresponding barriers when you read this value. I think it would be better if you use WRITE_ONCE() and READ_ONCE() APIs to manage this variable access. > + rcu_assign_pointer(ma->masks[i], ma->masks[ma->count]); > + RCU_INIT_POINTER(ma->masks[ma->count], NULL); > + > + kfree_rcu(mask, rcu); > + > + /* Shrink the mask array if necessary. */ > + if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) && > + ma->count <= (ma->max / 3)) > + tbl_mask_array_realloc(tbl, ma->max / 2); > } > > /* Remove 'mask' from the mask list, if it is not needed any more. */ > @@ -732,17 +741,8 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask) > BUG_ON(!mask->ref_count); > mask->ref_count--; > > - if (!mask->ref_count) { > - struct mask_array *ma; > - > - ma = ovsl_dereference(tbl->mask_array); > - tbl_mask_array_delete_mask(ma, mask); > - > - /* Shrink the mask array if necessary. */ > - if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) && > - ma->count <= (ma->max / 3)) > - tbl_mask_array_realloc(tbl, ma->max / 2); > - } > + if (!mask->ref_count) > + tbl_mask_array_del_mask(tbl, mask); > } > } > > @@ -795,17 +795,42 @@ static struct sw_flow_mask *flow_mask_find(const struct flow_table *tbl, > int i; > > ma = ovsl_dereference(tbl->mask_array); > - for (i = 0; i < ma->max; i++) { > + for (i = 0; i < ma->count; i++) { > struct sw_flow_mask *t; > t = ovsl_dereference(ma->masks[i]); > > - if (t && mask_equal(mask, t)) > + if (mask_equal(mask, t)) > return t; > } > > return NULL; > } > > +static int tbl_mask_array_add_mask(struct flow_table *tbl, > + struct sw_flow_mask *new) > +{ > + struct mask_array *ma = ovsl_dereference(tbl->mask_array); > + int err; > + > + if (ma->count >= ma->max) { > + err = tbl_mask_array_realloc(tbl, ma->max + > + MASK_ARRAY_SIZE_MIN); > + if (err) > + return err; > + > + ma = ovsl_dereference(tbl->mask_array); > + } > + > + BUG_ON(ovsl_dereference(ma->masks[ma->count])); > + > + rcu_assign_pointer(ma->masks[ma->count], new); > + > + smp_wmb(); > + ma->count++; > + > + return 0; > +} > + > /* Add 'mask' into the mask list, if it is not already there. */ > static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow, > const struct sw_flow_mask *new) > @@ -814,9 +839,6 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow, > > mask = flow_mask_find(tbl, new); > if (!mask) { > - struct mask_array *ma; > - int i; > - > /* Allocate a new mask if none exsits. */ > mask = mask_alloc(); > if (!mask) > @@ -825,29 +847,9 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow, > mask->range = new->range; > > /* Add mask to mask-list. */ > - ma = ovsl_dereference(tbl->mask_array); > - if (ma->count >= ma->max) { > - int err; > - > - err = tbl_mask_array_realloc(tbl, ma->max + > - MASK_ARRAY_SIZE_MIN); > - if (err) { > - kfree(mask); > - return err; > - } > - > - ma = ovsl_dereference(tbl->mask_array); > - } > - > - for (i = 0; i < ma->max; i++) { > - const struct sw_flow_mask *t; > - > - t = ovsl_dereference(ma->masks[i]); > - if (!t) { > - rcu_assign_pointer(ma->masks[i], mask); > - ma->count++; > - break; > - } > + if (tbl_mask_array_add_mask(tbl, mask)) { > + kfree(mask); > + return -ENOMEM; > } > } else { > BUG_ON(!mask->ref_count); > -- > 1.8.3.1 >
diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c index 4c82960..1b99f8e 100644 --- a/net/openvswitch/flow_table.c +++ b/net/openvswitch/flow_table.c @@ -198,10 +198,8 @@ static int tbl_mask_array_realloc(struct flow_table *tbl, int size) if (old) { int i; - for (i = 0; i < old->max; i++) { - if (ovsl_dereference(old->masks[i])) - new->masks[new->count++] = old->masks[i]; - } + for (i = 0; i < old->count; i++) + new->masks[new->count++] = old->masks[i]; } rcu_assign_pointer(tbl->mask_array, new); @@ -538,7 +536,7 @@ static struct sw_flow *flow_lookup(struct flow_table *tbl, mask = rcu_dereference_ovsl(ma->masks[i]); if (!mask) - continue; + break; flow = masked_flow_lookup(ti, key, mask, n_mask_hit); if (flow) { /* Found */ @@ -632,15 +630,13 @@ struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl, int i; /* Always called under ovs-mutex. */ - for (i = 0; i < ma->max; i++) { + for (i = 0; i < ma->count; i++) { struct table_instance *ti = rcu_dereference_ovsl(tbl->ti); u32 __always_unused n_mask_hit; struct sw_flow_mask *mask; struct sw_flow *flow; mask = ovsl_dereference(ma->masks[i]); - if (!mask) - continue; flow = masked_flow_lookup(ti, match->key, mask, &n_mask_hit); if (flow && ovs_identifier_is_key(&flow->id) && @@ -704,21 +700,34 @@ static struct table_instance *table_instance_expand(struct table_instance *ti, return table_instance_rehash(ti, ti->n_buckets * 2, ufid); } -static void tbl_mask_array_delete_mask(struct mask_array *ma, - struct sw_flow_mask *mask) +static void tbl_mask_array_del_mask(struct flow_table *tbl, + struct sw_flow_mask *mask) { + struct mask_array *ma = ovsl_dereference(tbl->mask_array); int i; /* Remove the deleted mask pointers from the array */ - for (i = 0; i < ma->max; i++) { - if (mask == ovsl_dereference(ma->masks[i])) { - RCU_INIT_POINTER(ma->masks[i], NULL); - ma->count--; - kfree_rcu(mask, rcu); - return; - } + for (i = 0; i < ma->count; i++) { + if (mask == ovsl_dereference(ma->masks[i])) + goto found; } + BUG(); + return; + +found: + ma->count--; + smp_wmb(); + + rcu_assign_pointer(ma->masks[i], ma->masks[ma->count]); + RCU_INIT_POINTER(ma->masks[ma->count], NULL); + + kfree_rcu(mask, rcu); + + /* Shrink the mask array if necessary. */ + if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) && + ma->count <= (ma->max / 3)) + tbl_mask_array_realloc(tbl, ma->max / 2); } /* Remove 'mask' from the mask list, if it is not needed any more. */ @@ -732,17 +741,8 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask) BUG_ON(!mask->ref_count); mask->ref_count--; - if (!mask->ref_count) { - struct mask_array *ma; - - ma = ovsl_dereference(tbl->mask_array); - tbl_mask_array_delete_mask(ma, mask); - - /* Shrink the mask array if necessary. */ - if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) && - ma->count <= (ma->max / 3)) - tbl_mask_array_realloc(tbl, ma->max / 2); - } + if (!mask->ref_count) + tbl_mask_array_del_mask(tbl, mask); } } @@ -795,17 +795,42 @@ static struct sw_flow_mask *flow_mask_find(const struct flow_table *tbl, int i; ma = ovsl_dereference(tbl->mask_array); - for (i = 0; i < ma->max; i++) { + for (i = 0; i < ma->count; i++) { struct sw_flow_mask *t; t = ovsl_dereference(ma->masks[i]); - if (t && mask_equal(mask, t)) + if (mask_equal(mask, t)) return t; } return NULL; } +static int tbl_mask_array_add_mask(struct flow_table *tbl, + struct sw_flow_mask *new) +{ + struct mask_array *ma = ovsl_dereference(tbl->mask_array); + int err; + + if (ma->count >= ma->max) { + err = tbl_mask_array_realloc(tbl, ma->max + + MASK_ARRAY_SIZE_MIN); + if (err) + return err; + + ma = ovsl_dereference(tbl->mask_array); + } + + BUG_ON(ovsl_dereference(ma->masks[ma->count])); + + rcu_assign_pointer(ma->masks[ma->count], new); + + smp_wmb(); + ma->count++; + + return 0; +} + /* Add 'mask' into the mask list, if it is not already there. */ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow, const struct sw_flow_mask *new) @@ -814,9 +839,6 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow, mask = flow_mask_find(tbl, new); if (!mask) { - struct mask_array *ma; - int i; - /* Allocate a new mask if none exsits. */ mask = mask_alloc(); if (!mask) @@ -825,29 +847,9 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow, mask->range = new->range; /* Add mask to mask-list. */ - ma = ovsl_dereference(tbl->mask_array); - if (ma->count >= ma->max) { - int err; - - err = tbl_mask_array_realloc(tbl, ma->max + - MASK_ARRAY_SIZE_MIN); - if (err) { - kfree(mask); - return err; - } - - ma = ovsl_dereference(tbl->mask_array); - } - - for (i = 0; i < ma->max; i++) { - const struct sw_flow_mask *t; - - t = ovsl_dereference(ma->masks[i]); - if (!t) { - rcu_assign_pointer(ma->masks[i], mask); - ma->count++; - break; - } + if (tbl_mask_array_add_mask(tbl, mask)) { + kfree(mask); + return -ENOMEM; } } else { BUG_ON(!mask->ref_count);