From: David Howells <dhowells@redhat.com>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Benjamin LaHaise <bcrl@kvack.org>,
Christoph Hellwig <hch@infradead.org>,
Suparna Bhattacharya <suparna@in.ibm.com>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org,
Linux Filesystem Development <linux-fsdevel@vger.kernel.org>,
linux-aio@kvack.org
Subject: Re: [RFC] Add support for semaphore-like structure with support for asynchronous I/O
Date: Sat, 16 Apr 2005 12:06:10 +0100 [thread overview]
Message-ID: <17024.1113649570@redhat.com> (raw)
In-Reply-To: <1113604974.27810.75.camel@lade.trondhjem.org>
Trond Myklebust <trond.myklebust@fys.uio.no> wrote:
>
> AFAICS You grab the wait_queue_t lock once in down()/__mutex_lock()
> order to try to take the lock (or queue the waiter if that fails), then
> once more in order to pass the mutex on to the next waiter on
> up()/mutex_unlock(). That is more or less the exact same thing I was
> doing with iosems using bog-standard waitqueues, and which Ben has
> adapted to his mutexes. What am I missing?
In Ben's patch it looks like the down() grabs the spinlock twice. Once to
queue yourself and one to dequeue yourself. The up() grabs the spinlock once
to wake you up, but it wasn't obvious that it actually dequeues you.
David
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next prev parent reply other threads:[~2005-04-16 11:06 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-30 21:51 [RFC] Add support for semaphore-like structure with support for asynchronous I/O Trond Myklebust
2005-03-30 22:34 ` Andrew Morton
2005-03-30 23:17 ` Trond Myklebust
2005-03-30 23:44 ` Andrew Morton
2005-03-31 0:02 ` Trond Myklebust
2005-03-31 22:53 ` Trond Myklebust
2005-04-01 0:13 ` Andrew Morton
2005-04-01 1:22 ` Trond Myklebust
2005-04-01 14:12 ` Suparna Bhattacharya
2005-04-04 15:52 ` Suparna Bhattacharya
2005-04-04 16:22 ` Benjamin LaHaise
2005-04-04 17:56 ` Trond Myklebust
2005-04-05 15:46 ` Benjamin LaHaise
2005-04-06 1:20 ` Trond Myklebust
2005-04-06 5:17 ` Bill Huey
2005-04-06 5:01 ` Suparna Bhattacharya
2005-04-07 11:43 ` Christoph Hellwig
2005-04-08 22:39 ` Benjamin LaHaise
2005-04-08 23:31 ` Trond Myklebust
2005-04-10 14:08 ` Suparna Bhattacharya
2005-04-15 16:13 ` David Howells
2005-04-15 22:42 ` Trond Myklebust
2005-04-15 23:42 ` Benjamin LaHaise
2005-04-16 11:12 ` David Howells
2005-04-16 11:06 ` David Howells [this message]
2005-04-04 16:39 ` Trond Myklebust
2005-03-31 8:02 ` Nikita Danilov
2005-03-31 12:31 ` Trond Myklebust
2005-03-31 17:09 ` Nikita Danilov
2005-03-31 17:22 ` Trond Myklebust
2005-03-31 17:32 ` Trond Myklebust
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