commit 03caea94f5675c55db7ba6c33b9a03fe4da519e4
Author: Stuart Haslam <[email protected]>
Date: Thu Apr 2 16:21:59 2015 +0100
linux-generic: support running with restricted cpu set
odp_cpu_count() returns the number of online CPUs, but when running in
a control group access may be restricted to only a subset of these.
This combined with a lack of error handling in odph_linux_pthread_create()
means a number of the applications create more threads than there are
cores available to them, leading to deadlocks in odp_barrier_wait().
-----Original Message-----
From: Benoît Ganne [mailto:[email protected]]
Sent: Tuesday, May 26, 2015 3:44 PM
To: Mike Holmes; Bulie Radu-Andrei-B37577
Cc: [email protected]
Subject: Re: [lng-odp] patch problem - "Support running with restricted cpuset"
Hi all,
I have an agenda conflict and won't be able to join the call today, however I
am interested in the subject. I can't find this patch in the ML nor in the
master or api-next odp git branches, could you point me to it, or even better,
post it on the ML for discussion?
I am a bit worried about the inclusion of cgroups into ODP.
Thanks,
ben
On 05/26/2015 02:28 PM, Mike Holmes wrote:
> Radu
>
> Can you join the opencall today to discuss this ?
> http://www.uberconference.com/opendataplane 4.00pm GMT
>
> Mike
>
> On 25 May 2015 at 04:37, Radu-Andrei Bulie <[email protected]
> <mailto:[email protected]>> wrote:
>
> Hi,____
>
> __ __
>
> The patch mentioned in the title is somehow related with the idea of
> odp threads isolation, I mean the odp data path threads.____
>
> I am not aware of any discussions regarding the cgroups to provide
> odp threads isolation nor some updates in the odp____
>
> API that will provide an integration with the cgroup library and
> cpusets usage.____
>
> As it is stated in the ODP documentation the odp data path threads
> are not controlled by the Linux scheduler - instead there is____
>
> a HW SoC level scheduler that manages them (or a specialized SW).
> This implies that there is not any strict dependency in isolating
> the odp threads by the rest____
>
> of the linux processes.____
>
> The problem introduced by this patch, on our platform, is that it
> restricts the usage of all cores available on the default scheduling
> domain provided by Linux.____
>
> And when I say all cores I include here the cores which are isolated
> from rest and do not participate in the load balancing scheme of the
> scheduler.(this is achieved____
>
> with the kernel boot time isolcpus). This cores will be used for the
> odp data path threads and will be assigned explicitly at threads'
> creation time.____
>
> Thus the Linux scheduler will load balance processes(threads) on the
> non-isolated cores.(these will be the odp control path
> threads).____
>
> The exact problem of the patch is that - to determine the number of
> cores available for threads' creation - it uses the
> pthread_getaffinity_np function (and not____
>
> _SC_NPROCESSORS_ONLN as before) which will return all the cores on
> which a threads is eligible to run - that is all the cores that
> participate in the Linux ____
>
> load balancing scheme. In this situation(with this patch), on our
> platform, we are able to create, for example, just one thread - on
> core 0, which is used for control, because____
>
> the other cores 1..n which are isolated, are not visible using the
> function mentioned above.(and as I said they will be used for the
> fast path processing)____
>
> As a conclusion, an action should be taken regarding the mentioned
> patch.____
>
> __ __
>
> __ __
>
> Regards,____
>
> __ __
>
> Radu____
>
>
> _______________________________________________
> lng-odp mailing list
> [email protected] <mailto:[email protected]>
> https://lists.linaro.org/mailman/listinfo/lng-odp
>
>
>
>
> --
> Mike Holmes
> Technical Manager - Linaro Networking Group Linaro.org
> <http://www.linaro.org/>***│ *Open source software for ARM SoCs
>
> __
>
>
>
>
> _______________________________________________
> lng-odp mailing list
> [email protected]
> https://lists.linaro.org/mailman/listinfo/lng-odp
>
--
Benoît GANNE
Field Application Engineer, Kalray
+33 (0)648 125 843
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