From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <001201c022e4$d6defe00$426514d4@cz99.cz>
From: "Jakub Jermar" <jj@comberg.cz>
To: <9fans@cse.psu.edu>
References: <20001110130656.CD862199EA@mail.cse.psu.edu>
Subject: Re: [9fans] sleep(), sched() and ilock()
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Date: Wed, 20 Sep 2000 11:22:57 +0200
Topicbox-Message-UUID: 27f7f2ee-eac9-11e9-9e20-41e7f4b1d025

There is a misunderstanding that I probably introduced to this thread. I was
asking two separate things: (i) how's it with ilock() and (ii) how's it with
sleep(). I certainly didn't want to put any relation between them. Sorry for
getting you confused. Now I see that my questions should have been asked
separately or at least better separated. You have answered both of the
questions in your first reply.

If you want to know where does this confusion comes from, it is from my
private kernel notes I am taking. A time ago I found out that ilock() and
iunlock()  run on the same cpu. Yesterday I reread the
notes again and I could not decide whether this fact is the goal of ilock()
or just a side effect.

The second question came up from the same notes, but had completely
different subject. It talked about sleep(), because I couldn't take easy the
fact that splhi can save the state on one cpu and splx it on another. But as
I've already replied, I perceived that that doesn't matter.

> The splx is necessary because ...... we need to return in the
> same state we arrived.

This is my point. Do we need to have the cpu in the same state as it
appeared before sleep() or does this sentence relate to processes executing
sleep()?
After your first reply and further glancing through sleep(), I would say the
latter is true.

Thanks for your patience,
Jakub Jermar