[Babel-users] time, syscall, etc.

[kerneis at pps.jussieu.fr]

Matthieu,

On Fri, Jul 15, 2011 at 07:55:55PM +0200, Matthieu Boutier wrote:
> Is FD_ZERO a non-raming* syscall?

FD_ZERO is really nothing more than a memset.  (It is not even a syscall
actually.)

> It seems necessary to do a gettime(&now); only after select (in the other
> case we don't have wait anything). So I think it's better to put gettime in
> the "if" statement. If you think that checking for the next timeout may take
> a consequent time, so put the first "gettime" just before the "if".

But it's easier to read that way, you do not need to think about it for a long
time to convince yourself that now is really now (and gettimeofday is not
that expensive in most cases).


> babel.c, somewhere near 590-610:
> if(errno != EAGAIN && errno != EINTR) {
>     perror("recv");
>     sleep(1);
> }
> Euhm… why blocking the entire rest of the program just because of a EAGAIN ?
> Don't we would sleep (if necessary) at the "select" ?

Well select told you there are data available, but you cannot read them:
something is going wrong.  You do not want to trigger a busy loop if this
behaviour happens several times in a row, so you just sleep a bit for things to
calm down ;-)

Best,
-- 
Gabriel