From: Paolo Ornati <ornati@fastwebnet.it>
To: "Sorin Manolache" <sorinm@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: newbie questions about while (1) in kernel mode and spinlocks
Date: Thu, 21 Dec 2006 11:20:00 +0100 [thread overview]
Message-ID: <20061221112000.67722190@localhost> (raw)
In-Reply-To: <20170a030612210141y6578602eo525e6df5f324747d@mail.gmail.com>
On Thu, 21 Dec 2006 10:41:44 +0100
"Sorin Manolache" <sorinm@gmail.com> wrote:
> spin_lock(&lck);
> down(&sem); /* I know that one shouldn't sleep when holding a lock */
> /* but I want to understand why */
I suppose because the lock is held for an indefinite amount of time and
any other process that try to get that lock will "spin" and burn CPU
without doing anything useful (locking the process in kernel mode and
preventing the execution of other processes on that CPU if there
isn't any type of PREEMPTION).
:)
spin_lock is a "while(1) {...}" thing...
--
Paolo Ornati
Linux 2.6.20-rc1-g99f5e971 on x86_64
next prev parent reply other threads:[~2006-12-21 10:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-21 9:41 newbie questions about while (1) in kernel mode and spinlocks Sorin Manolache
2006-12-21 10:05 ` Paolo Ornati
2006-12-21 10:20 ` Paolo Ornati [this message]
2006-12-21 10:40 ` Paolo Ornati
2006-12-21 23:54 ` Steven Rostedt
[not found] <fa.D8ff1OmLNpVeVOoaJAP7ENpm+Wk@ifi.uio.no>
2006-12-21 14:31 ` Robert Hancock
-- strict thread matches above, loose matches on Subject: below --
2006-12-21 18:14 SR, Krishna
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20061221112000.67722190@localhost \
--to=ornati@fastwebnet.it \
--cc=linux-kernel@vger.kernel.org \
--cc=sorinm@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox