From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: "Tan, Jianfeng" <jianfeng.tan@intel.com>,
"Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Cc: "Richardson, Bruce" <bruce.richardson@intel.com>,
"thomas@monjalon.net" <thomas@monjalon.net>
Subject: Re: [dpdk-dev] [PATCH v3 2/3] eal: add synchronous multi-process communication
Date: Thu, 25 Jan 2018 18:02:57 +0000 [thread overview]
Message-ID: <b57c9112-2fcb-f629-f562-21ddc3aee6c3@intel.com> (raw)
In-Reply-To: <3178bc08-02d4-9020-853f-a8a71f39bb50@intel.com>
On 25-Jan-18 5:10 PM, Tan, Jianfeng wrote:
>
>
> On 1/26/2018 12:22 AM, Burakov, Anatoly wrote:
>> On 25-Jan-18 3:03 PM, Ananyev, Konstantin wrote:
>>>
>>>
>>>> -----Original Message-----
>>>> From: Burakov, Anatoly
>>>> Sent: Thursday, January 25, 2018 1:10 PM
>>>> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Tan,
>>>> Jianfeng <jianfeng.tan@intel.com>; dev@dpdk.org
>>>> Cc: Richardson, Bruce <bruce.richardson@intel.com>; thomas@monjalon.net
>>>> Subject: Re: [dpdk-dev] [PATCH v3 2/3] eal: add synchronous
>>>> multi-process communication
>>>>
>>>> On 25-Jan-18 1:05 PM, Burakov, Anatoly wrote:
>>>>> On 25-Jan-18 1:00 PM, Ananyev, Konstantin wrote:
>>>>>>
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Burakov, Anatoly
>>>>>>> Sent: Thursday, January 25, 2018 12:26 PM
>>>>>>> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Tan,
>>>>>>> Jianfeng
>>>>>>> <jianfeng.tan@intel.com>; dev@dpdk.org
>>>>>>> Cc: Richardson, Bruce <bruce.richardson@intel.com>;
>>>>>>> thomas@monjalon.net
>>>>>>> Subject: Re: [PATCH v3 2/3] eal: add synchronous multi-process
>>>>>>> communication
>>>>>>>
>>>>>>> On 25-Jan-18 12:19 PM, Ananyev, Konstantin wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: Burakov, Anatoly
>>>>>>>>> Sent: Thursday, January 25, 2018 12:00 PM
>>>>>>>>> To: Tan, Jianfeng <jianfeng.tan@intel.com>; dev@dpdk.org
>>>>>>>>> Cc: Richardson, Bruce <bruce.richardson@intel.com>; Ananyev,
>>>>>>>>> Konstantin <konstantin.ananyev@intel.com>; thomas@monjalon.net
>>>>>>>>> Subject: Re: [PATCH v3 2/3] eal: add synchronous multi-process
>>>>>>>>> communication
>>>>>>>>>
>>>>>>>>> On the overall patch,
>>>>>>>>>
>>>>>>>>> Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
>>>>>>>>>
>>>>>>>>> For request(), returning number of replies received actually makes
>>>>>>>>> sense, because now we get use the value to read our replies, if we
>>>>>>>>> were
>>>>>>>>> a primary process sending messages to secondary processes.
>>>>>>>>
>>>>>>>> Yes, I also think it is good to return number of sends.
>>>>>>>> Then caller can compare number of sended requests with number of
>>>>>>>> received replies and decide should it be considered a failure or
>>>>>>>> no.
>>>>>>>>
>>>>>>>
>>>>>>> Well, OK, that might make sense. However, i think it would've be
>>>>>>> of more
>>>>>>> value to make the API consistent (0/-1 on success/failure) and put
>>>>>>> number of sent messages into the reply, like number of received.
>>>>>>> I.e.
>>>>>>> something like
>>>>>>>
>>>>>>> struct reply {
>>>>>>> int nb_sent;
>>>>>>> int nb_received;
>>>>>>> };
>>>>>>>
>>>>>>> We do it for the latter already, so why not the former?
>>>>>>
>>>>>> The question is what treat as success/failure?
>>>>>> Let say we sent 2 requests (of 3 possible), got back 1 response...
>>>>>> Should we consider it as success or failure?
>>>>>>
>>>>>
>>>>> I think "failure" is "something went wrong", not "secondary processes
>>>>> didn't respond". For example, invalid parameters, or our socket
>>>>> suddenly
>>>>> being closed, or some other error that prevents us from sending
>>>>> requests
>>>>> to secondaries.
>>>>>
>>>>> As far as i can tell from the code, there's no way to know if the
>>>>> secondary process is running other than by attempting to connect to
>>>>> it,
>>>>> and get a response. So, failed connection should not be a failure
>>>>> condition, because we can't know if we *can* connect to the process
>>>>> until we do. Process may have ended, but socket files will still be
>>>>> around, and there's nothing we can do about that. So i wouldn't
>>>>> consider
>>>>> inability to send a message a failure condition.
>>>>>
>>>>
>>>> Just to clarify - i'm suggesting leaving this decision up to the user.
>>>> If a user expects there to be "n" processes running, but only "m"
>>>> responses were received, he could treat it as error. Another user might
>>>> simply send periodical updates/polls to secondaries, for whatever
>>>> reason
>>>> (say, stats display), and won't really care if one of them just
>>>> died, so
>>>> there's no error for that user.
>>>>
>>>> However, all of this has nothing to do with API. If we're able to send
>>>> messages - it's not a failure. If we can't - it is. That's the part API
>>>> should be concerned about, and that's what the return value should
>>>> indicate, IMO.
>>>
>>> Ok so to clarify, you are suggesting:
>>> we have N peers - if send_msg() returns success for all N - return
>>> success
>>> (no matter did we get a reply or not)
>>> Otherwise return a failure.
>>> ?
>>> Konstantin
>>
>> More along the lines of, return -1 if and only if something went
>> wrong. That might be invalid parameters, or that might be an error
>> with our own socket,
>
> To check if the error is caused by our own socket, we check the errno
> after sendmsg?
>
> Like for remote socket errors, we check:
> - ECONNRESET
> - ECONNREFUSED
> - ENOBUFS
>
> Right?
>
> Thanks,
> Jianfeng
Well, that was only an example. If it doesn't make much sense to do so
in this case, then don't, and only return -1 on invalid parameters.
AFAIU we're using connectionless sockets so a bunch of these errors
won't be applicable to us. Maybe -ENOBUFS, but i'm not sure it's worth
it to check for that.
>
>
>> or something else to that effect. In all other cases, return 0 (that
>> includes cases where we sent N messages but M replies where N != M).
>> So, in other words, return 0 if we *could have succeeded* if nothing
>> went wrong on the other side, and only return -1 if something went
>> wrong on our side.
>>
>>>
>>>
>>>>
>>>> --
>>>> Thanks,
>>>> Anatoly
>>
>>
>
>
--
Thanks,
Anatoly
next prev parent reply other threads:[~2018-01-25 18:03 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-30 18:44 [dpdk-dev] [PATCH 0/3] generic channel for " Jianfeng Tan
2017-11-30 18:44 ` [dpdk-dev] [PATCH 1/3] eal: add " Jianfeng Tan
2017-12-11 11:04 ` Burakov, Anatoly
2017-12-11 16:43 ` Ananyev, Konstantin
2017-11-30 18:44 ` [dpdk-dev] [PATCH 2/3] eal: add synchronous " Jianfeng Tan
2017-12-11 11:39 ` Burakov, Anatoly
2017-12-11 16:49 ` Ananyev, Konstantin
2017-11-30 18:44 ` [dpdk-dev] [PATCH 3/3] vfio: use the generic multi-process channel Jianfeng Tan
2017-12-11 12:01 ` Burakov, Anatoly
2017-12-11 9:59 ` [dpdk-dev] [PATCH 0/3] generic channel for multi-process communication Burakov, Anatoly
2017-12-12 7:34 ` Tan, Jianfeng
2017-12-12 16:18 ` Burakov, Anatoly
2018-01-11 4:07 ` [dpdk-dev] [PATCH v2 0/4] " Jianfeng Tan
2018-01-11 4:07 ` [dpdk-dev] [PATCH v2 1/4] eal: add " Jianfeng Tan
2018-01-13 12:57 ` Burakov, Anatoly
2018-01-15 19:52 ` Ananyev, Konstantin
2018-01-11 4:07 ` [dpdk-dev] [PATCH v2 2/4] eal: add and del secondary processes in the primary Jianfeng Tan
2018-01-13 13:11 ` Burakov, Anatoly
2018-01-15 21:45 ` Ananyev, Konstantin
2018-01-11 4:07 ` [dpdk-dev] [PATCH v2 3/4] eal: add synchronous multi-process communication Jianfeng Tan
2018-01-13 13:41 ` Burakov, Anatoly
2018-01-16 0:00 ` Ananyev, Konstantin
2018-01-16 8:10 ` Tan, Jianfeng
2018-01-16 11:12 ` Ananyev, Konstantin
2018-01-16 16:47 ` Tan, Jianfeng
2018-01-17 10:50 ` Ananyev, Konstantin
2018-01-17 13:09 ` Tan, Jianfeng
2018-01-17 13:15 ` Tan, Jianfeng
2018-01-17 17:20 ` Ananyev, Konstantin
2018-01-11 4:07 ` [dpdk-dev] [PATCH v2 4/4] vfio: use the generic multi-process channel Jianfeng Tan
2018-01-13 14:03 ` Burakov, Anatoly
2018-03-04 14:57 ` [dpdk-dev] [PATCH v5] vfio: change to use " Jianfeng Tan
2018-03-14 13:27 ` Burakov, Anatoly
2018-03-19 6:53 ` Tan, Jianfeng
2018-03-20 10:33 ` Burakov, Anatoly
2018-03-20 10:56 ` Burakov, Anatoly
2018-03-20 8:50 ` [dpdk-dev] [PATCH v6] " Jianfeng Tan
2018-04-05 14:26 ` Tan, Jianfeng
2018-04-05 14:39 ` Burakov, Anatoly
2018-04-12 23:27 ` Thomas Monjalon
2018-04-12 15:26 ` Burakov, Anatoly
2018-04-15 15:06 ` [dpdk-dev] [PATCH v7] " Jianfeng Tan
2018-04-15 15:10 ` Tan, Jianfeng
2018-04-17 23:04 ` Thomas Monjalon
2018-01-25 4:16 ` [dpdk-dev] [PATCH v3 0/3] generic channel for multi-process communication Jianfeng Tan
2018-01-25 4:16 ` [dpdk-dev] [PATCH v3 1/3] eal: add " Jianfeng Tan
2018-01-25 10:41 ` Thomas Monjalon
2018-01-25 11:27 ` Burakov, Anatoly
2018-01-25 11:34 ` Thomas Monjalon
2018-01-25 12:21 ` Ananyev, Konstantin
2018-01-25 4:16 ` [dpdk-dev] [PATCH v3 2/3] eal: add synchronous " Jianfeng Tan
2018-01-25 12:00 ` Burakov, Anatoly
2018-01-25 12:19 ` Ananyev, Konstantin
2018-01-25 12:25 ` Burakov, Anatoly
2018-01-25 13:00 ` Ananyev, Konstantin
2018-01-25 13:05 ` Burakov, Anatoly
2018-01-25 13:10 ` Burakov, Anatoly
2018-01-25 15:03 ` Ananyev, Konstantin
2018-01-25 16:22 ` Burakov, Anatoly
2018-01-25 17:10 ` Tan, Jianfeng
2018-01-25 18:02 ` Burakov, Anatoly [this message]
2018-01-25 12:19 ` Burakov, Anatoly
2018-01-25 12:22 ` Ananyev, Konstantin
2018-01-25 4:16 ` [dpdk-dev] [PATCH v3 3/3] vfio: use the generic multi-process channel Jianfeng Tan
2018-01-25 10:47 ` Thomas Monjalon
2018-01-25 10:52 ` Burakov, Anatoly
2018-01-25 10:57 ` Thomas Monjalon
2018-01-25 12:15 ` Burakov, Anatoly
2018-01-25 19:14 ` [dpdk-dev] [PATCH v4 0/2] generic channel for multi-process communication Jianfeng Tan
2018-01-25 19:14 ` [dpdk-dev] [PATCH v4 1/2] eal: add synchronous " Jianfeng Tan
2018-01-25 19:14 ` [dpdk-dev] [PATCH v4 2/2] vfio: use the generic multi-process channel Jianfeng Tan
2018-01-25 19:15 ` [dpdk-dev] [PATCH v4 0/2] generic channel for multi-process communication Tan, Jianfeng
2018-01-25 19:21 ` [dpdk-dev] [PATCH v5 " Jianfeng Tan
2018-01-25 19:21 ` [dpdk-dev] [PATCH v5 1/2] eal: add " Jianfeng Tan
2018-01-25 19:21 ` [dpdk-dev] [PATCH v5 2/2] eal: add synchronous " Jianfeng Tan
2018-01-25 21:23 ` [dpdk-dev] [PATCH v5 0/2] generic channel for " Thomas Monjalon
2018-01-26 3:41 ` [dpdk-dev] [PATCH v6 " Jianfeng Tan
2018-01-26 3:41 ` [dpdk-dev] [PATCH v6 1/2] eal: add " Jianfeng Tan
2018-01-26 10:25 ` Burakov, Anatoly
2018-01-29 6:37 ` Tan, Jianfeng
2018-01-29 9:37 ` Burakov, Anatoly
2018-01-26 3:41 ` [dpdk-dev] [PATCH v6 2/2] eal: add synchronous " Jianfeng Tan
2018-01-26 10:31 ` Burakov, Anatoly
2018-01-29 23:52 ` [dpdk-dev] [PATCH v6 0/2] generic channel for " Thomas Monjalon
2018-01-30 6:58 ` [dpdk-dev] [PATCH v7 " Jianfeng Tan
2018-01-30 6:58 ` [dpdk-dev] [PATCH v7 1/2] eal: add " Jianfeng Tan
2018-01-30 6:58 ` [dpdk-dev] [PATCH v7 2/2] eal: add synchronous " Jianfeng Tan
2018-01-30 14:46 ` [dpdk-dev] [PATCH v7 0/2] generic channel for " Thomas Monjalon
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