[Xcb] GTK-XCB is in progress

[Vincent Torri]

Maybe that could go into the tutorial too (in the part # 18)

Vincent

On Wed, 8 Nov 2006, Jeremy Kolb wrote:

> Hi Bart,
>
> Can you put that on the wiki?  It would clear up some confusion...
> especially when porting xlib programs to xcb.
>
> Jeremy
>
> Barton C Massey wrote:
>> In message <934b4cdf0611072334j6c42d5b9i15f988e0834e3281 at mail.gmail.com> you wrote:
>>> Oh, maybe I haven't made use of the round-trip delays sufficiently. I
>>> understand that it is obvious to use round-trip when many requests are sent
>>> in a loop, so we can get the cookies together, then ask for all the replies.
>>> But in many situations that a single request is sent, we cannot suppress the
>>> round-trips. Is that?
>>
>> The general ruleset I always intended for using a cookie to
>> hide latency is this:
>>   1. Always send a request as soon as you legally can.
>>   2. Never force the returned cookie until you actually need
>>      to examine the result.
>> In the presence of multiple requests, it gets a bit more
>> complicated.
>>   1. Always send each request as soon as you legally can.
>>      1a. If you can send multiple requests at the same time,
>>          send the one whose value you expect to need first,
>>          first.
>>          1b. If rule 1a doesn't help, a secondary tiebreaker
>>              is that it's better to send requests the server
>>              can process quickly first, followed by those
>>              the server might run slowly.
>>   2. Never force a returned cookie until you actually need
>>      to examine the result.
>>
>> The idea of rule 1b is that if you're lucky, you can be
>> working on the quick results while the server is processing
>> the slow request.  In general, don't worry about ordering of
>> simultaneous requests too much.  It's hard to construct a
>> realistic example where these kinds of corner cases matter.
>>
>> Note that rule 2 is stronger than necessary in the presence
>> of multiple requests. If you need to force a cookie returned
>> for a request r, it is harmless to also force cookies
>> returned from requests earlier than r: these values will be
>> available anyway, since the server always returns results in
>> order.  However, it is also harmless to wait to force a
>> cookie until you need the value, and it makes it clearer
>> that you've done the right thing.
>>
>> If you follow these rules, you will be getting about all the
>> latency hiding you can expect from what is a fundamentally
>> serialized protocol without using threading or some
>> equivalent mechanism.
>>
>> Hope this helps.  Comment welcome.
>>
>> 	Bart
>> _______________________________________________
>> Xcb mailing list
>> Xcb at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/xcb
>
>
> -- 
> Ce message a été vérifié par MailScanner
> pour des virus ou des polluriels et rien de
> suspect n'a été trouvé.
> Message délivré par le serveur de messagerie de l'Université d'Evry.
>
>