From: Ursula Braun <ubraun@linux.vnet.ibm.com>
To: Leon Romanovsky <leon@kernel.org>
Cc: davem@davemloft.net, netdev@vger.kernel.org,
linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org,
jwi@linux.vnet.ibm.com, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com, raspl@linux.vnet.ibm.com
Subject: Re: [PATCH net-next 08/10] net/smc: introduce a delay
Date: Wed, 20 Sep 2017 16:37:04 +0200 [thread overview]
Message-ID: <a8d7b051-8f43-3e21-714f-50d7faa53e0e@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170920140315.GR5788@mtr-leonro.local>
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On 09/20/2017 04:03 PM, Leon Romanovsky wrote:
> On Wed, Sep 20, 2017 at 01:58:11PM +0200, Ursula Braun wrote:
>> The number of outstanding work requests is limited. If all work
>> requests are in use, tx processing is postponed to another scheduling
>> of the tx worker. Switch to a delayed worker to have a gap for tx
>> completion queue events before the next retry.
>>
>
> How will delay prevent and protect the resource exhausting?
>
> Thanks
>
SMC runs with a fixed number of in-flight work requests per QP (constant
SMC_WR_BUF_CNT) to prevent resource exhausting. If all work requests are
currently in use, sending of another work request has to wait till some
outstanding work request is confirmed via send completion queue. If sending
is done in a context which is not allowed to wait, the tx_worker is
scheduled instead.
With this patch a small delay is added to avoid too many unsuccessful send
retries due to a still ongoing "all work requests in use" condition.
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next prev parent reply other threads:[~2017-09-20 14:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170920115813.63745-1-ubraun@linux.vnet.ibm.com>
2017-09-20 11:58 ` [PATCH net-next 01/10] net/smc: add missing dev_put Ursula Braun
2017-10-02 20:36 ` Parav Pandit
2017-10-02 20:39 ` Parav Pandit
2017-10-05 7:54 ` Ursula Braun
2017-10-05 14:44 ` Parav Pandit
2017-09-20 11:58 ` [PATCH net-next 02/10] net/smc: add receive timeout check Ursula Braun
2017-09-20 11:58 ` [PATCH net-next 04/10] net/smc: adjust net_device refcount Ursula Braun
2017-09-20 11:58 ` [PATCH net-next 05/10] net/smc: adapt send request completion notification Ursula Braun
2017-09-20 11:58 ` [PATCH net-next 06/10] net/smc: longer delay for client link group removal Ursula Braun
2017-09-20 11:58 ` [PATCH net-next 07/10] net/smc: terminate link group if out-of-sync is received Ursula Braun
2017-09-20 11:58 ` [PATCH net-next 08/10] net/smc: introduce a delay Ursula Braun
2017-09-20 14:03 ` Leon Romanovsky
2017-09-20 14:37 ` Ursula Braun [this message]
2017-09-20 11:58 ` [PATCH net-next 09/10] net/smc: parameter cleanup in smc_cdc_get_free_slot() Ursula Braun
2017-09-20 11:58 ` [PATCH net-next 10/10] net/smc: no close wait in case of process shut down Ursula Braun
2017-09-20 23:29 ` [PATCH net-next 00/10] net/smc: updates 2017-09-20 David Miller
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