From: Steven Rostedt <rostedt@goodmis.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: local_add_return
Date: Mon, 15 Dec 2008 08:47:35 -0500 (EST) [thread overview]
Message-ID: <alpine.DEB.1.10.0812150823370.18692@gandalf.stny.rr.com> (raw)
Hi Rusty,
I'm trying to make the ring buffers lockless and reentrant. It is slowly
going that way. The local_add_return is to reserve a part of the ring
buffer even when an interrupt can come in and reserver part of that same
ring buffer. The atomic add here has to only be atomic with respect to
interrupts.
On intel, there is no reason to use a LOCK increment, since the ring
buffers are per cpu. A simple asm inc would work. I was thinking that is
what local_add_return gives me. I could replace the local_add_returns with
atomic_add_return, but that just seems to be adding overhead for archs
that do not need it.
Shouldn't local_add_return be a way for archs that can increment a memory
location atomically against interrupts to use that infrastructure? It can
simply fall back to atomic_add_return for those archs that do not have
a lesser equivalent of atomic_add_return.
-- Steve
next reply other threads:[~2008-12-15 13:47 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-15 13:47 Steven Rostedt [this message]
2008-12-16 6:33 ` local_add_return Rusty Russell
2008-12-16 6:57 ` local_add_return David Miller
2008-12-16 7:13 ` local_add_return David Miller
2008-12-16 22:38 ` local_add_return Rusty Russell
2008-12-16 22:50 ` local_add_return Rusty Russell
2008-12-16 23:25 ` local_add_return Luck, Tony
2008-12-16 23:25 ` local_add_return Luck, Tony
2008-12-16 23:43 ` local_add_return Heiko Carstens
2008-12-16 23:43 ` local_add_return Heiko Carstens
2008-12-16 23:59 ` local_add_return Eric Dumazet
2008-12-16 23:59 ` local_add_return Eric Dumazet
2008-12-17 0:01 ` local_add_return Mathieu Desnoyers
2008-12-17 0:01 ` local_add_return Mathieu Desnoyers
2008-12-18 22:52 ` local_add_return Rusty Russell
2008-12-18 22:53 ` local_add_return Rusty Russell
2008-12-19 3:35 ` local_add_return Mathieu Desnoyers
2008-12-19 3:35 ` local_add_return Mathieu Desnoyers
2008-12-19 5:54 ` local_add_return Rusty Russell
2008-12-19 5:54 ` local_add_return Rusty Russell
2008-12-19 17:06 ` local_add_return Mathieu Desnoyers
2008-12-19 17:06 ` local_add_return Mathieu Desnoyers
2008-12-20 1:33 ` local_add_return Rusty Russell
2008-12-20 1:45 ` local_add_return Rusty Russell
2008-12-20 1:33 ` local_add_return Rusty Russell
2008-12-22 18:43 ` local_add_return Mathieu Desnoyers
2008-12-22 18:43 ` local_add_return Mathieu Desnoyers
2008-12-24 11:42 ` local_add_return Rusty Russell
2008-12-24 11:54 ` local_add_return Rusty Russell
2008-12-24 18:53 ` local_add_return Mathieu Desnoyers
2008-12-24 18:53 ` local_add_return Mathieu Desnoyers
2008-12-16 16:25 ` local_add_return Mathieu Desnoyers
2008-12-17 11:23 ` local_add_return Rusty Russell
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=alpine.DEB.1.10.0812150823370.18692@gandalf.stny.rr.com \
--to=rostedt@goodmis.org \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rusty@rustcorp.com.au \
/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.