Date: Wed, 27 Sep 2000 15:13:27 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: non@ever.sanda.gr.jp Cc: freebsd-current@FreeBSD.ORG, freebsd-mobile@FreeBSD.ORG Subject: Re: [CFR] ncv, nsp, stg SCSI drivers Message-ID: <48276.970060407@critter> In-Reply-To: Your message of "Wed, 27 Sep 2000 22:08:38 %2B0900." <20000927220838X.non@ever.sanda.gr.jp>
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In message <20000927220838X.non@ever.sanda.gr.jp>, non@ever.sanda.gr.jp writes:
>From: Poul-Henning Kamp <phk@critter.freebsd.dk>
>Date: Wed, 27 Sep 2000 15:01:13 +0200
>> >I would like to have review especially on the changes in
>> >i386/isa/clock.c for counting delay loop numbers,
>>
>> Could you explain the functionality you need here ? We already
>> have a DELAY() macro/function in the kernel...
>
>There are codes like;
> int tout = sc->sc_wc;
> ;
> while (slp->sl_scp.scp_datalen > 0 && tout -- > 0)
> {
> ;
> }
>
>To calculate the tout we use;
> sc->sc_wc = delaycount * 2000; /* 2 sec */
>
>And we initialize the delaycount in clock.c.
This is called "busy polling" and there must be a better way to do it.
Has this code been profiled to examine typical actual delay lengths ?
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD coreteam member | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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