[Development] Performance of QUdpSocket writeDatagram between Qt4 and Qt5 in different GNU/Linux platforms

[Mauro Brenna]

Hello Jan,

Thanks for the suggestion.

The answer is YES they are behaving quite differently:

Here the output while in the for loop:

QT4.8.5


sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19
sendto(7, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET,
sin_port=htons(45454), sin_addr=inet_addr("255.255.255.255")}, 16) = 19


QT 5.1.1


sendto(6, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET6,
sin6_port=htons(45454), inet_pton(AF_INET6, "::ffff:255.255.255.255",
&sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 19
socket(PF_FILE, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="", ???}) = -1 ENODEV (No such device)
close(7)                                = 0
sendto(6, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET6,
sin6_port=htons(45454), inet_pton(AF_INET6, "::ffff:255.255.255.255",
&sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 19
socket(PF_FILE, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="", ???}) = -1 ENODEV (No such device)
close(7)                                = 0
sendto(6, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET6,
sin6_port=htons(45454), inet_pton(AF_INET6, "::ffff:255.255.255.255",
&sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 19
socket(PF_FILE, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="", ???}) = -1 ENODEV (No such device)
close(7)                                = 0
sendto(6, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET6,
sin6_port=htons(45454), inet_pton(AF_INET6, "::ffff:255.255.255.255",
&sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 19
socket(PF_FILE, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="", ???}) = -1 ENODEV (No such device)
close(7)                                = 0
sendto(6, "Broadcast message 0", 19, MSG_NOSIGNAL, {sa_family=AF_INET6,
sin6_port=htons(45454), inet_pton(AF_INET6, "::ffff:255.255.255.255",
&sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 19
socket(PF_FILE, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="", ???}) = -1 ENODEV (No such device)
close(7)                                = 0

What can I do to have the same behaviour as QT 4.8.5. It sounds like a QT5
.1.1 is trying to set a connection or something like that.

Kind regards,

Mauro







On 25 February 2014 18:46, Jan Kundrát <jkt at flaska.net> wrote:

> On Tuesday, 25 February 2014 16:56:53 CEST, Mauro Brenna wrote:
> >  I looked a bit in the qt code and saw a bind() inside the QT5
> > writeDatagram method, which I do not immediately understand but I do not
> > know if might cause the issue.
>
> Is there any difference in `strace` when you instrument the Qt4 and Qt5
> versions of the test?
>
> Cheers,
> Jan
>
> --
> Trojitá, a fast Qt IMAP e-mail client -- http://trojita.flaska.net/
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