[srslte-users] srsenb&ue running on ubuntu vs centos

[alexander.serkin at gmail.com]

Strace output:
...
fcntl(14, F_SETFL, O_RDONLY|O_NONBLOCK) = 0
write(1, "Waiting PHY to initialize ... ", 30Waiting PHY to initialize ... ) = 30
futex(0x7fe2806f2060, FUTEX_WAIT_PRIVATE, 2, NULL) ###! The delay is here !###  = 0
futex(0x7fe2806f2060, FUTEX_WAKE_PRIVATE, 1) = 0
write(1, "done!\n", 6done!

And the problem persists after reinstalling the VM from centos back to ubuntu 18.

-----Original Message-----
From: alexander.serkin at gmail.com <alexander.serkin at gmail.com> 
Sent: Friday, March 26, 2021 1:44 PM
To: 'Cedric Roux' <cedric.roux at eurecom.fr>; 'Andre Puschmann' <andre.puschmann at softwareradiosystems.com>; srslte-users at lists.softwareradiosystems.com
Subject: RE: [srslte-users] srsenb&ue running on ubuntu vs centos

Hi Cedric
Not sure I did all correct, but I changed rrc.cc that way:
..
#include <random>
..
using namespace std;
..
  // set seed (used in CHAP auth and attach)
  // srand(tv.tv_usec);
  mt19937 mt_rand(tv.tv_usec);
...

And that did not help - the delay seems to occur somewhere later on after the call to srand or mt_rand. And even after the rrc init procedure:

10:41:33.131890 [NAS ] [I] Read security ctxt from file .ctxt. ksi: 5, k_asme: a99f174aa53110ed5020762235c7ccf7012099cc8406e2a68a9472b201cdb9a8, tx_count: 4, rx_count: 3, int_alg: 1, enc_alg: 0
10:41:33.131935 [RRC ] [I] using mt_rand of 131931
10:41:33.131943 [RRC ] [I] mt_rand ended. starting ue_required_sibs.assign
10:41:33.131944 [RRC ] [I] ue_required_sibs.assign ended Ooops...
10:41:58.497617 [MAC ] [I] [   11] mac::get_metrics started

Cheers,
Alex

-----Original Message-----
From: Cedric Roux <cedric.roux at eurecom.fr>
Sent: Friday, March 26, 2021 12:48 PM
To: Andre Puschmann <andre.puschmann at softwareradiosystems.com>; alexander.serkin at gmail.com; srslte-users at lists.softwareradiosystems.com
Subject: Re: [srslte-users] srsenb&ue running on ubuntu vs centos



On 2021-03-25 16:19, Andre Puschmann wrote:
> Hey Alex,
> 
> On 24/3/21 10:10, alexander.serkin at gmail.com wrote:
>> Despite the fact that centos VM has twice more cpus and 8 times more 
>> RAM comparing to ubuntu, the srsue starts there >20 seconds while on 
>> ubuntu machine it takes 2-3 seconds.
> 
> we've actually observed the same on some configuration. Yet, I've not 
> come to find the cause. I was suspecting the srand() which we should

maybe there is an access to /dev/random?
Reading data from /dev/random can be slow, based on the activity of the computer.
You can check with strace maybe.

> probably not use anyhow and instead port to C++ std::mt19937, like we 
> already do elsewhere in the code
> 
> If you can reliably reproduce that, try to change to std::mt19937 and 
> see if that improves the start up time.
> 
> Thanks
> Andre
> 
>>
>> The delay occurs between two UE log messages. CentOS:
>>
>> 08:55:21.243251 [NAS ] [I] Read security ctxt from file .ctxt. ksi: 
>> 6,
>> k_asme:
>> b03a9dc5106b1c09e96b14a11ed34afe128d632bea9509b902fadeae01669ce3,
>> tx_count: 4, rx_count: 3, int_alg: 1, enc_alg: 0
>>
>> 08:55:21.243307 [RRC ] [I] using srand seed of 243303
>>
>> 08:55:40.753622 [MAC ] [I] [    0] DL retx: 0.00 %, perpkt: 0.00, UL
>> retx: 0.00 % perpkt: 0.00
>>
>> 08:55:40.753726 [RLC ] [I] LCID=0, RX throughput: 0.000000 Mbps. TX
>> throughput: 0.000000 Mbps.
>>
>>   
>>
>> Ubuntu:
>>
>> 08:58:46.389003 [NAS ] [I] Read security ctxt from file .ctxt. ksi: 
>> 6,
>> k_asme:
>> 0417d4c4d86b4d272a061cc3ae49f177722fe64870e7a7aec63d47033162be6d,
>> tx_count: 14, rx_count: b, int_alg: 1, enc_alg: 0
>>
>> 08:58:46.389025 [RRC ] [I] using srand seed of 389022
>>
>> 08:58:47.075794 [MAC ] [I] [    0] DL retx: 0.00 %, perpkt: 0.00, UL
>> retx: 0.00 % perpkt: 0.00
>>
>> 08:58:47.075809 [RLC ] [I] LCID=0, RX throughput: 0.000000 Mbps. TX
>> throughput: 0.000000 Mbps.
>>
>>   
>>
>> I wonder if there probably exist some simple explanation of this ?
>>
>>   
>>
>> Cheers,
>>
>> Alex
>>
>>
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>> srslte-users at lists.softwareradiosystems.com
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>>
> 
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