From: William Tu <u9012063@gmail.com>
To: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Cc: Greg Rose <gvrose8192@gmail.com>, pravin shelar <pshelar@ovn.org>,
"<dev@openvswitch.org>" <dev@openvswitch.org>,
Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: [ovs-dev] [PATCH net-next v4 05/10] net: openvswitch: optimize flow-mask looking up
Date: Mon, 21 Oct 2019 10:58:43 -0700 [thread overview]
Message-ID: <CALDO+SaxFBBAvuxnxc8F9fho8eqByVdCavoBcteRRaWLgFU_tA@mail.gmail.com> (raw)
In-Reply-To: <CAMDZJNVXwkTgFSC7XtANLdF4j_ygQSpVrvq8KaY23czP8FRbBw@mail.gmail.com>
> > Hi Tonghao,
> >
> > Does this improve performance? After all, the original code simply
> > check whether the mask is NULL, then goto next mask.
> I tested the performance, but I disable the mask cache, and use the
> dpdk-pktgen to generate packets:
> The test ovs flow:
> ovs-dpctl add-dp system@ovs-system
> ovs-dpctl add-if system@ovs-system eth6
> ovs-dpctl add-if system@ovs-system eth7
>
> for m in $(seq 1 100 | xargs printf '%.2x\n'); do
> ovs-dpctl add-flow ovs-system
> "in_port(1),eth(dst=00:$m:00:00:00:00/ff:ff:ff:ff:ff:$m),eth_type(0x0800),ipv4(frag=no)"
> 2
> done
>
> ovs-dpctl add-flow ovs-system
> "in_port(1),eth(dst=98:03:9b:6e:4a:f5/ff:ff:ff:ff:ff:ff),eth_type(0x0800),ipv4(frag=no)"
> 2
> ovs-dpctl add-flow ovs-system
> "in_port(2),eth(dst=98:03:9b:6e:4a:f4/ff:ff:ff:ff:ff:ff),eth_type(0x0800),ipv4(frag=no)"
> 1
>
> for m in $(seq 101 160 | xargs printf '%.2x\n'); do
> ovs-dpctl add-flow ovs-system
> "in_port(1),eth(dst=00:$m:00:00:00:00/ff:ff:ff:ff:ff:$m),eth_type(0x0800),ipv4(frag=no)"
> 2
> done
>
> for m in $(seq 1 100 | xargs printf '%.2x\n'); do
> ovs-dpctl del-flow ovs-system
> "in_port(1),eth(dst=00:$m:00:00:00:00/ff:ff:ff:ff:ff:$m),eth_type(0x0800),ipv4(frag=no)"
> done
>
> Without this patch: 982481pps (64B)
> With this patch: 1112495 pps (64B), about 13% improve
>
Hi Tonghao,
Thanks for doing the measurement.
Based on the result (skipping 100 NULL mask lookup with 13% improvement),
and with additional overhead of mask cache being invalidate while
refilling these 100
gap, I'd argue that this patch is not necessary. But let's wait for
others comments.
Regards,
William
> > However, with your patch, isn't this invalidated the mask cache entry which
> > point to the "M" you swap to the front? See my commands inline.
> >
> > >
> > > Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
> > > Tested-by: Greg Rose <gvrose8192@gmail.com>
> > > ---
<snip>
> > > static struct table_instance *table_instance_expand(struct table_instance *ti,
> > > @@ -704,21 +704,33 @@ 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)
> > > {
> > > - int i;
> > > + struct mask_array *ma = ovsl_dereference(tbl->mask_array);
> > > + int i, ma_count = READ_ONCE(ma->count);
> > >
> > > /* 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:
> > > + WRITE_ONCE(ma->count, ma_count -1);
> > > +
> > > + rcu_assign_pointer(ma->masks[i], ma->masks[ma_count -1]);
> > > + RCU_INIT_POINTER(ma->masks[ma_count -1], NULL);
> >
> > So when you swap the ma->masks[ma_count -1], the mask cache entry
> > who's 'mask_index == ma_count' become all invalid?
> Yes, a little tricky.
> > Regards,
> > William
> >
next prev parent reply other threads:[~2019-10-21 17:59 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-15 10:30 [PATCH net-next v4 00/10] optimize openvswitch flow looking up xiangxia.m.yue
2019-10-15 10:30 ` [PATCH net-next v4 01/10] net: openvswitch: add flow-mask cache for performance xiangxia.m.yue
2019-10-18 23:29 ` [ovs-dev] " William Tu
2019-10-15 10:30 ` [PATCH net-next v4 02/10] net: openvswitch: convert mask list in mask array xiangxia.m.yue
2019-10-18 23:30 ` [ovs-dev] " William Tu
2019-10-15 10:30 ` [PATCH net-next v4 03/10] net: openvswitch: shrink the mask array if necessary xiangxia.m.yue
2019-10-18 23:33 ` [ovs-dev] " William Tu
2019-10-15 10:30 ` [PATCH net-next v4 04/10] net: openvswitch: optimize flow mask cache hash collision xiangxia.m.yue
2019-10-15 10:30 ` [PATCH net-next v4 05/10] net: openvswitch: optimize flow-mask looking up xiangxia.m.yue
2019-10-18 23:26 ` [ovs-dev] " William Tu
2019-10-21 4:51 ` Tonghao Zhang
2019-10-21 17:58 ` William Tu [this message]
2019-10-15 10:30 ` [PATCH net-next v4 06/10] net: openvswitch: simplify the flow_hash xiangxia.m.yue
2019-10-18 23:27 ` [ovs-dev] " William Tu
2019-10-15 10:30 ` [PATCH net-next v4 07/10] net: openvswitch: add likely in flow_lookup xiangxia.m.yue
2019-10-18 23:27 ` [ovs-dev] " William Tu
2019-10-15 10:30 ` [PATCH net-next v4 08/10] net: openvswitch: fix possible memleak on destroy flow-table xiangxia.m.yue
2019-10-17 22:38 ` Pravin Shelar
2019-10-18 3:16 ` Tonghao Zhang
2019-10-18 18:12 ` Pravin Shelar
2019-10-21 5:01 ` Tonghao Zhang
2019-10-22 6:57 ` Pravin Shelar
2019-10-23 2:35 ` Tonghao Zhang
2019-10-24 7:14 ` Pravin Shelar
2019-10-28 6:49 ` Tonghao Zhang
2019-10-29 7:37 ` Pravin Shelar
2019-10-29 11:30 ` Tonghao Zhang
2019-10-29 20:27 ` Pravin Shelar
2019-10-15 10:30 ` [PATCH net-next v4 09/10] net: openvswitch: don't unlock mutex when changing the user_features fails xiangxia.m.yue
2019-10-18 23:27 ` [ovs-dev] " William Tu
2019-10-15 10:30 ` [PATCH net-next v4 10/10] net: openvswitch: simplify the ovs_dp_cmd_new xiangxia.m.yue
2019-10-18 23:29 ` [ovs-dev] " William Tu
2019-10-17 19:22 ` [PATCH net-next v4 00/10] optimize openvswitch flow looking up David Miller
2019-10-17 20:29 ` Gregory Rose
2019-10-21 17:14 ` [ovs-dev] " William Tu
2019-10-22 1:16 ` Tonghao Zhang
2019-10-22 15:44 ` William Tu
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