Does FreeBSD have sendmmsg or recvmmsg system calls?

[Boris Astardzhiev]

>Hi Boris,
>thanks for working on this.
>
>A few comments:
>
>- do you have any performance data on calling *mmsg() versus
>  multiple invocations of the equivalent *msg() ?

No, I don't for now.

>- in the following chunk in recvmmsg.c , there are slight
>  type differences between the function and the internal cast.
>  Same in sendmmsg.c
>
>    +ssize_t
>    +recvmmsg(int s, struct mmsghdr *msgvec, unsigned int vlen, int flags)
>    +{
>    +
>    +       return (((int (*)(int, struct mmsghdr *, int, int))
>    +           __libc_interposing[INTERPOS_recvmmsg])(s, msgvec, vlen,
flags));
>    +}

I see. I'll fix it.

>- why did you add a cap_rights_init() to the functions when
>  neither sendmsg or recvmsg have it (in other words, this is
>  a worthwhile addition but perhaps should be done later

I need to grab access to so_error due to error handling. send/recvmmsg()
would have to return the number of datagrams sent/rcvd. send/recvmsg()
return the number of characters sent/rcvd. Thus I followed Konstantin's
explanation regarding so_error.

>- the initial part of the two functions sys_*mmsg() is almost
>  exactly the same so can you define a function with the common code ?
>- you could probably avoid the repeated malloc/free of the iov
>  with a first loop that finds the max iov size and does the allocation
>  only once. copyiniov can then be replaced by a copyin

I'll try to optimize the calls at the end. I like the suggestion though and
I'll scrutinize over it.

>- (minor) what is the point of copying the current entry into msg rather
than
>  just using mp-> ...

Just my style for making things more readable to me.

>- can you add a comment explaining why you do the following
>
>               error = copyout(&td->td_retval[0], &uap->msgvec[i].msg_len,
>                   sizeof(td->td_retval[0]));

Thank you. I'll add a comment for clarification.

Best Regards,
Boris Astardzhiev

On Thu, Jan 7, 2016 at 12:56 PM, Luigi Rizzo <rizzo at iet.unipi.it> wrote:

> Hi Boris,
> thanks for working on this.
>
> A few comments:
>
> - do you have any performance data on calling *mmsg() versus
>   multiple invocations of the equivalent *msg() ?
>
> - in the following chunk in recvmmsg.c , there are slight
>   type differences between the function and the internal cast.
>   Same in sendmmsg.c
>
>     +ssize_t
>     +recvmmsg(int s, struct mmsghdr *msgvec, unsigned int vlen, int flags)
>     +{
>     +
>     +       return (((int (*)(int, struct mmsghdr *, int, int))
>     +           __libc_interposing[INTERPOS_recvmmsg])(s, msgvec, vlen,
> flags));
>     +}
>
>
> - why did you add a cap_rights_init() to the functions when
>   neither sendmsg or recvmsg have it (in other words, this is
>   a worthwhile addition but perhaps should be done later
>
> - the initial part of the two functions sys_*mmsg() is almost
>   exactly the same so can you define a function with the common code ?
>
> - you could probably avoid the repeated malloc/free of the iov
>   with a first loop that finds the max iov size and does the allocation
>   only once. copyiniov can then be replaced by a copyin
>
> - (minor) what is the point of copying the current entry into msg rather
> than
>   just using mp-> ...
>
> - can you add a comment explaining why you do the following
>
>                error = copyout(&td->td_retval[0], &uap->msgvec[i].msg_len,
>                    sizeof(td->td_retval[0]));
>
>
> cheers
> luigi
>
> On Thu, Jan 7, 2016 at 1:51 AM, Boris Astardzhiev
> <boris.astardzhiev at gmail.com> wrote:
> > Hello,
> >
> > Here's my implementation of the two system calls. The patch is against
> HEAD
> > from a couple of days:
> > commit ff9e83788d7ed52342dcba4dff1e62fdf3cc985c
> > Author: ngie <ngie at FreeBSD.org>
> > Date:   Mon Jan 4 03:34:22 2016 +0000
> >
> >     Remove free'ing of an uninitialized variable
> >
> >     Just remove it completely from the test as it's initialized but
> unused
> > apart
> >     from the free(3) call
> >
> >     Differential Revision: https://reviews.freebsd.org/D4769 (part of
> > larger diff)
> >     MFC after: 5 days
> >     Reported by: cppcheck
> >     Reviewed by: oshogbo
> >     Sponsored by: EMC / Isilon Storage Division
> >
> > I've made brief tests using the examples in the manpages in Linux
> skipping
> > the timeout stuff:
> > http://man7.org/linux/man-pages/man2/sendmmsg.2.html
> > http://man7.org/linux/man-pages/man2/recvmmsg.2.html
> >
> > I've tried to stick to the comments in the thread but any
> > suggestions/testings
> > are also welcomed so that I can fix the calls accordingly.
> >
> > Regards,
> > Boris Astardzhiev
> >
> >
> > On Mon, Jan 4, 2016 at 11:07 PM, Mark Delany <c2h at romeo.emu.st> wrote:
> >
> >> > You just repeat arguments for the text in my messages, which you
> removed
> >> > on reply.
> >>
> >> My goal is to get you to scruitinize.
> >>
> >> Thank you for helping.
> >>
> >>
> >> Mark.
> >> _______________________________________________
> >> freebsd-net at freebsd.org mailing list
> >> https://lists.freebsd.org/mailman/listinfo/freebsd-net
> >> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
> >>
> >
> > _______________________________________________
> > freebsd-net at freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-net
> > To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>
>
>
> --
> -----------------------------------------+-------------------------------
>  Prof. Luigi RIZZO, rizzo at iet.unipi.it  . Dip. di Ing. dell'Informazione
>  http://www.iet.unipi.it/~luigi/        . Universita` di Pisa
>  TEL      +39-050-2217533               . via Diotisalvi 2
>  Mobile   +39-338-6809875               . 56122 PISA (Italy)
> -----------------------------------------+-------------------------------
>