[ovs-dev] Openflow 1.4: Eviction mechanism implementation
Saloni Jain
saloni.jain at tcs.com
Thu Sep 11 12:04:34 UTC 2014
Hi Ben/Team,
We have started with the implementation of eviction feature as per openflow specification 1.4. Following points needs discussion:
1. As per current implementation, "ovs-vsctl create table ... overflow-policy=evict" command, configures openvswitch database(conf.db) and sets table structure eviction fields and eviction groups.
2. As per our understanding, the implementation of eviction for importance as per openflow specification 1.4, should be in parallel with existing functionality, i.e. if eviction for importance is set through mod-table command and importance parameter is given by the user,then we must create the eviction groups(eviction_group_add_rule) and at the time of eviction, obtain the value on basis of importance from this group.
3. This approach requires table->eviction_field which is set only when create table command with overflow-policy=evict is given.
4. mod-table command for setting the eviction parameter as importance will only set the table config parameter as "importance" and will not set the table->eviction fields.
5. So as per our understanding this should be mandatory to first enable eviction on the complete table using create table ... overflow-policy=evict and then change the mode of eviction as importance using mod-table command.
Kindly comment on the above mentioned approach.
Thanks in advance for your suggestions/feedback.
Thanks and Regards,
Saloni Jain
Tata Consultancy Services
Mailto: saloni.jain at tcs.com
Website: http://www.tcs.com
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-----Ben Pfaff <blp at nicira.com> wrote: -----
To: Saloni Jain <saloni.jain at tcs.com>
From: Ben Pfaff <blp at nicira.com>
Date: 09/09/2014 08:25PM
Cc: dev at openvswitch.org, Hiteshi Madan <hiteshi.madan at tcs.com>, Deepankar Gupta <deepankar.gupta at tcs.com>
Subject: Re: [ovs-dev] Openflow 1.4: Eviction mechanism implementation
On Tue, Sep 09, 2014 at 05:15:06PM +0530, Saloni Jain wrote:
> 1. If eviction on the switch is set on the basis of "lifetime" by
> create table command and then the command for "importance" (mod-table
> command) is given then what will be the basis of eviction in this
> case. Will in this case, eviction will be performed on the basis of
> importance only and not lifetime i.e, second value will overwrite the
> previously configured eviction policy?
I'd expect it to consider one of those policies first and then use the
other as a tie-breaker, e.g. consider importance first, then use
lifetime for entries of equal importance.
However, this might turn out to be difficult or not useful, and if so
then using just one of the policies would make sense (probably
importance in this case).
> 3. If eviction performed on basis of "lifetime" using create table
> command, we can disable it using create table command setting
> overflow-policy=refuse. Similarly if eviction is done for importance
> using mod-table command, then how it can be disabled?
Also using mod-table to turn the eviction flag off.
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