Date: Tue, 06 Jul 1999 10:33:16 -0700 (PDT) From: John Polstra <jdp@polstra.com> To: "Brian F. Feldman" <green@FreeBSD.org> Cc: hackers@FreeBSD.org Subject: Re: poll() vs select() Message-ID: <XFMail.990706103316.jdp@polstra.com> In-Reply-To: <Pine.BSF.4.10.9907061327110.4140-100000@janus.syracuse.net>
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Brian F. Feldman wrote:
> On Tue, 6 Jul 1999, John Polstra wrote:
>
>> In article <Pine.BSF.4.10.9907042155090.66085-100000@janus.syracuse.net>,
>>
>> The application itself has to get involved if it wants to do async
>> name lookups, or async anything else, for that matter. Suppose you
>> do have an async thread to do hostname lookups as you propose. What
>> is the application going to do while that thread is waiting for the
>> lookup to complete? It depends on the application, and thus it has
>> to be coded into the application. Maybe there's nothing useful the
>> application could do until the lookup returns.
>>
>> I've been told that it works fine to use libc_r and put the name
>> lookups into a separate thread. But to take advantage of it, the
>> application has to have something useful it wants to do (and can do)
>> in the meantime.
>
> It would let the other threads run more while the lookup is occurring.
> Wouldn't that be the most natural expectation of it? Or would this
> be too hard without kernel-assisted threading?
What I'm saying is, we already have that in multi-threaded
applications. The system can't just provide it automatically to
single-threaded applications; they wouldn't know how to take advantage
of it. In other words:
* Multi-threaded applications already have it.
* Single-threaded applications can't use it.
John
---
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"No matter how cynical I get, I just can't keep up." -- Nora Ephron
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