From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Corey Minyard <minyard@acm.org>
Cc: Arjan van de Ven <arjan@infradead.org>, Greg KH <greg@kroah.com>,
Sergey Vlasov <vsu@altlinux.ru>,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] New operation for kref to help avoid locks
Date: Wed, 02 Mar 2005 11:02:33 +1100 [thread overview]
Message-ID: <42250299.8080709@yahoo.com.au> (raw)
In-Reply-To: <4224FC33.6040405@acm.org>
Corey Minyard wrote:
> Arjan van de Ven wrote:
>
>>> Just doing an atomic operation is not faster than doing a lock, an
>>> atomic operation, then an unlock? Am I missing something?
>>>
>>
>>
>> if the lock and the atomic are on the same cacheline they're the same
>> cost on most modern cpus...
>>
>>
> Ah, I see. Not likely to ever be the case with this. The lock will
> likely be with the main data structure (the list, or whatever) and the
> refcount will be in the individual item in the main data structure (list
> entry).
>
Is get_with_check actually going to be useful for anything? It
seems like it promotes complex and potentially unsafe schemes.
eg. In your queue example, it would usually be better to have
a refcount for being on queue, and entry_completed would remove
the entry from the queue and accordingly drop the refcount. The
release function would then just free it.
next prev parent reply other threads:[~2005-03-02 0:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-26 15:55 [PATCH] New operation for kref to help avoid locks Corey Minyard
2005-02-26 20:20 ` Sergey Vlasov
2005-02-26 22:23 ` Corey Minyard
2005-03-01 20:15 ` Greg KH
2005-03-01 21:02 ` Arjan van de Ven
2005-03-01 21:24 ` Greg KH
2005-03-01 21:54 ` Corey Minyard
2005-03-01 22:14 ` Arjan van de Ven
2005-03-01 23:35 ` Corey Minyard
2005-03-02 0:02 ` Nick Piggin [this message]
2005-03-02 0:28 ` Corey Minyard
2005-03-02 0:34 ` Nick Piggin
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=42250299.8080709@yahoo.com.au \
--to=nickpiggin@yahoo.com.au \
--cc=arjan@infradead.org \
--cc=greg@kroah.com \
--cc=linux-kernel@vger.kernel.org \
--cc=minyard@acm.org \
--cc=vsu@altlinux.ru \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.